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ELECTRIC  HEATING 

BY 
E.  A.  WILCOX,  E.  E. 

Member  A.  I.  E.  E. 

ELECTRIC  HEATING   SPECIALIST 

GREAT  WESTERN  POWER 

COMPANY 


Fird   Thousand 


SAN  FRANCISCO 

TECHNICAL  PUBLISHING  COMPANY 

CROSSLEY  BUILDING 

LONDON 

E.  &  F.  N.  SPON,  LIMITED 

57  HAYMARKET 

1916 


COPYRIGHT,  1916 

BY 

TECHNICAL  PUBLISHING 

COMPANY 


/ 


t-1 


PREFACE 

The  utilization  of  electricity  for  heating  purposes 
on  a  large  scale  is  a  development  so  recent  that  little 
information  on  the  subject  has  yet  been  published 
outside  of  the  trade  periodicals.  The  wealth  of  printed 
matter  concerning  electric  lighting  practice  only  em- 
phasizes the  dearth  of  data  regarding  electric  heating. 
Yet  heat  by  wire  seems  destined  to  a  far  greater  fu- 
ture than  light  by  wire,  not  only  as  regards  the  amount 
of  current  consumed,  but  also  in  the  intrinsic  value  of 
its  service  to  mankind. 

In  his  capacity  as  a  load  builder  for  central  sta- 
tions the  author  was  early  confronted  with  the  lack  of 
recorded  facts  about  the  how  and  why  of  electric  heat- 
ing. For  his  personal  needs  he  correlated  widely- 
scattered  notes,  simplified  the  technical  treatment  so 
that  it  would  be  intelligible  to  the  sales  prospect  and 
brought  into  convenient  form  much  of  the  knowledge 
required  by  the  salesman  of  electric  heating  appliances. 
This  information  has  been  so  useful  to  the  author 
that  it  was  thought  that  it  might  also  be  of  service 
to  others  in  the  industry,  particularly  since  the  elec- 
tric cooking  load  has  become  so  desirable  to  the  cen- 
tral station.     Hence  this  book. 

Briefly,  it  aims  to  set  forth  in  a  practical  way  the 
many  uses  to  which  electric  heat  may  be  applied.  The 
advantages  and  disadvantages  of  various  kinds  of  heat- 
ing loads  are  compared  and  many  types  of  heating 
devices  are  explained.     The  relative  operating  costs  of 


365508 


electric  and  fuel-heated  apparatus  are  shown  by  tables 
and  simple  calculations.  Suggestions  are  given  re- 
garding approved  methods  of  installing  and  using  do- 
mestic and  commercial  ranges,  bake  ovens,  water 
heaters  and  industrial  heating  devices. 

Acknowledgement  is  here  made  of  the  courtesy  of 
many  manufacturers  in  supplying  cuts  used  to  illus- 
trate typical  equipment. 

E.  A.  WILCOX. 
San  Francisco,  July,  1916. 


TABLE  OF  CONTENTS 

CHAPTER  I.                                       Page 
Heat   Energy   and   Electricity 1 

Deman  1  for  Heat — Advantages  of  Electric  Heat — 
Natui'e  of  Heat — Temperature  Measurement — Meas- 
urement of  Heat — Specific  Heat — Thermal  Capacity 
— The  Calorie — Mechanical  Equivalent  of  Heat — 
Relation  to  Electrical  Units — Latent  Heat — Radi- 
ation— Conduction — Convection — Comparison  of  Fuel 
11  nd    Electric   Heat. 

CHAPTER  n. 

Domestic  Lamp  Socket  Heating  Devices 8 

Importance  —  Electric  Irons  —  Electric  Stoves  — 
Toaster  Stoves  —  Chafing  Dishes  —  Coffee  Perco- 
lators— Tea  Samovars — Tea  Kettles — Table  Cook- 
ing Outfits — Electric  Grills — Food  Warmers — Plate 
Warmers  and  Hot  Closets — Bake  Ovens — Nursery 
Milk  Warmers — Curling  Iron  Heaters — Warming 
Pads— Immersion  Heaters — Other  Household  De- 
vices. 

CHAPTER  HI. 

Installation   of  Heating  Apparatus 19 

Correct  Installation — Wiring  for  Heating  Appa- 
ratus— Carrying  Capacities  of  Wires — Correct  Volt- 
age— Methods  of  Wiring — Exp6sed  Knob  and  Cleat 
Wiring — Flexible  Metallic  Conduit — Flexible  Steel 
Armored  Conductor — Switches — Grounding — Ranges 
in  Apartment  Houses  and  Flats — Proper  Position 
for   a    Range. 

CHAPTER  IV. 

Electric   Cooking 26 

The  March  of  Progress — Advantages  of  Electric 
Cooking — Facility  of  Operation — Reduction  in  Meat 
Shrinkage — Importance  of  Proper  Utensils — Econ- 
omy in  Range  Operation — Elimination  of  Kitchen 
Chimneys — Operation  by  Servants — Attention  to 
Range  Users — Electric  Cooking  in  Schools — Elec- 
tric Cooking  in  Apartment  Houses — Preparation  of 
Food. 

CHAPTER  V. 

The  Electric  Range 42 

Demand — Essential  Qualifications — Types  of  Heat- 
ing  Units — Types   of   Electric   Ranges. 

CHAPTER  VI. 

Commercial   Cooking 68 

Opportunities — Advantages — Apparatus  Available — 
Hotel  Ranges — Meat  Broilers — Hot  Closets— Steam 
Tables — AVater  Heaters — Frying  Kettles — Toasters 
— Coffee   Urns — Griddles — Electric   Bake   Ovens. 

CHAPTER  VII. 

Electric  Water  Heating 9?. 

Comparison  of  Fuel  and  Electricity — Thermal  Char- 
acteristics of  Water- — Electric  Energy  Required — 
Heat  Losses — Lagging — Methods  of  Heating  Water 
Electrically — Essential  Features — Automatic  Tem- 
perature and  Time  Control  Devices — Installation  of 
Thermal    Storage    Water    Heaters. 

CHAPTER  Vin. 

Electric  Heating  of  Buildings 115 

Use  and  Advantages — Comparative  Costs  of  Fuel 
and  Electric  Heat — Electric  Heating  Systems — 
Radiant  Heaters  —  Convection  Heaters  —  Oil  and 
Water  Radiators — Indirect  Air  Heaters — Steam  and 
Hot  Water  Systems — Installation  of  Electric  Heat- 
ers— Calculation    of   Heat    Requirements. 


CHAPTER  IX.                                      Page 
Industrial    Heating 130 

Scope  of  Application — Development  of  Field — 
Advantages  of  Electric  Heat — Comparison  with 
Fuel  and  Steam  Heat — Heating  Elements — Heating- 
Specifications — Applications  of  Electric  Heat  (60 
industries). 

CHAPTER  X. 

Electric  Furnaces 145 

Economic  Advantages — Field — Character  of  Service 
— Classification — Advantages  and  Limitations — Heat 
Energy  Required — Furnace  Walls — Furnace  Elec- 
trodes. 

CHAPTER  XI. 

Electric  Furnace  Applications 156 

Fundamental  Considerations — Production  of  Ferro- 
.  Alloys — Smelting  of  Iron  and  Other  Ores — PioJuc- 
tion  of  Graphite  and  Carbide — Electrolytic  Furnace 
Processes — Aluminum — Nitrates — Steel  —  Resistance 
Furnaces — Induction  Furnaces — Arc  Furnaces. 
CHAPTER  XII. 

Low  Temperature  Electric  Furnaces  and  Ovens 174 

Field — Advantages — Processes — Carbon  Resistance 
Type — Metallic  Resistance  Type — Selection — Enam- 
eling Ovens — Equipping  Fuel  Ovens  for  Electric 
Heat — Revolving  Type  Ovens — Drying  Ovens — Heat 
Losses    Through    Oven    Walls. 

CHAPTER  XIII. 
Incubating   and   Brooding 185 

Modern  Methods — Poultry  Incubating — Electric  In- 
cubators— Advantages — Relative  Operating  Costs — 
Brooding  of  Chickens — Electric  Brooders — Advan- 
tages— Relative   Costs   of   Operation. 

CHAPTER  XIV. 
Electric  Welding 197 

Nature  of  Welding — Processes — Arc  Welding — Com- 
parative Costs — Resistance  Welding — Welding  Vari- 
ous  Metals — Energy   Requirements. 

CHAPTER  XV. 
Electric    Steam    Boilers 214 

Application — Advantages  —  Calculations  —  Efficien- 
cies— Energy  Requirements — Steam  Boiler  Appar- 
atus. 

CHAPTER  XVI. 

General  Applications  of  Electric  Heat 221 

Diversity  of  Use — Automobile  Heater — Bacteriolog- 
ical Incubators — Bath  Cabinets — Beer  Vat  Dryers — 
Branding  Irons — Button  Die  Heater — Can  Capping — 
Candy  Batch  Warmer — Celluloid  Embossers — Choc- 
olate Warmers — Corn-Popping  Machines — ^Dryers 
of  all  kinds — Embossing  Press  Heaters — Engravers' 
Stoves — Flask  Heaters — Gilding  Wheel  Heaters — 
Glove  Stretchers — Glue-Pots — Hatters'  Tools — Heat- 
ing Units — Hot  Plates— Irons — Linotype  Pots — 
Liquid  Heaters — Meat  Branders — Metal  Melting — 
Number  Brander — Oil  Tempering  Baths — Pallette  Die 
Heaters — Paper  Seal  Moistenei* — Paper  Warmers —  . 
Peanut  Roaster — Perforator — Pipe  Thawer — Pitch 
Kettles — Shoe  Machinery — Solder  Pots  and  Irons — 
Sterilizers — Tire  Vulcanizers — Water  Stills — Weight 
Redvicer — Yarn     Conditioner. 

CHAPTER  XVII. 
Rates  for  Heating  Service 258 

Establishing  of  Rates — Heating  Loads — Rate 
Makers'  Difficulties— N.  E.  L.  A.  Rate  Principles — 
Application    to   Heating   Rates. 

Appendix 261 


HEAT  ENERGY  AND  ELECTRICITY        3 

raise  the  temperature  of  one  pound  of  any  substance 
one  degree  Fahrenheit. 

A  clear  conception  of  the  use  of  this  unit  of  meas- 
urement is  essential  to  the  designer  of  heating  appa- 
ratus, since  it  indicates  the  capacity  for  absorbing  heat 
for  a  given  temperature  change.  All  the  heat  taken  up 
in  raising  the  temperature  of  a  substance  is  given  off 
when  the  body  cools.  The  total  heat  absorbed  by  a 
body  is  equivalent  to  the  product  obtained  by  multi- 
plying temperature  difference,  weight,  and  specific 
heat.  It  will  be  noted  from  the  table  in  the  back  of 
the  book  that  the  specific  heat  of  water  (i.e.,  its  heat 
absorbing  power)  is  greater  than  that  of  most  known 
substances. 

Thermal  Capacity. — The  thermal  capacity  of  a 
substance  is  the  quantity  of  heat  required  to  raise  its 
temperature  one  degree.  It  is  the  product  of  its  spe- 
cific heat  and  mass.  As  the  specific  heat  of  water  is 
unity,  fifteen  pounds  of  water  has  a  thermal  capacity 
of  15  X  1  ^  15  B.t.u.  Likewise  the  specific  heat  of 
cast  iron  being  .1298,  fifteen  pounds  of  iron  has  a 
thermal  capacity  of  15  X  .1298=  1.947  B.t.u. 

The  Calorie. — Heating  calculations  are  frequently 
expressed  in  calories  instead  of  British  thermal  units. 
The  French  thermal  unit,  or  calorie,  is  that  quantity 
of  heat  required  to  raise  the  temperature  of  one  kilo- 
gramme of  water  one  degree  Centigrade.  It  is  equiv- 
alent to  3.968  British  thermal  units ;  or  one  British 
thermal  units  is  equal  to  .252  calorie. 

Mechanical  Equivalent  of  Heat. — Heat  and  me- 
chanical energy  are  mutually  convertible.  The  num- 
ber of  foot-pounds  of  medhanical  energy  equivalent  to 
one  British  thermal  unit  is  the  mechanical  equiv- 
alent of  heat.  It  has  been  established  experimentally 
that  one  B.t.u.  is  equal  to  778  foot-pounds,  and  on  that 
basis  it  has  been  calculated  that  one  horsepower  is 
equivalent  to  2545  B.t.u.  per  hour. 

Relation  to  Electrical  Units. — Where  resistance  is 
offered  to  the  flow  of  an  electric  current  the  electric 
energy  is  converted  into  heat  energy.     The  heat  gen- 


4  ELECTRIC     HEATING 

erated  is  proportional  to  the  resistance  of  the  con- 
ductor, the  square  of  the  current  strength,  and  the 
length  of  time  the  current  flows.  It  has  been  estab- 
lished experimentally  that  one  ampere  of  current  flow- 
ing through  a  resistance  of  one  ohm  for  one  hour  will 
generate  3.412  B.t.u..  Since  one  ampere  flowing  one 
hour  through  a  resistance  of  one  ohm  is  equivalent 
to  one  watt-hour,  3.412  B.t.u.  equals  one  watt-hour 
(EIT=RrT)  or  3412  B.t.u.  equals  one  kilowatt  hour. 
If  it  is  desired  to  raise  a  certain  quantity  of  a 
substance  through  a  certain  temperature  range  the 
number  of  kilowatt  hours  required  for  the  operation 
may  be  calculated  as  follows : 

Degrees  rise  F.  X  Pounds  X  Specific  Heat 
Kw-hr.  =  %  Efficiency  X  3412 

Divide  the  number  of  kilowatt  hours  determined 
by  the  above  calculations  by  the  number  of  hours 
allowed  for  the  operation  and  the  result  will  be  the 
kilowatts  of  heater  capacity  required  far  perform- 
ing the  work. 

Latent  Heat. — The  quantity  of  heat  which  is  ab- 
sorbed by  a  body  in  a  given  state  in  converting  it 
into  another  state  without  changing  its  temperature  is 
termed  its  latent  heat. 

Latent  heat  of  fusion  is  the  heat  absorbed  in 
changing  a  body  of  a  certain  weight  from  a  solid  to  a 
liquid  without  changing  its  temperature.  When  the 
operation  is  reversed  the  same  quantity  of  heat  is 
given  oflf  as  was  previously  absorbed. 

Latent  heat  of  evaporation  is  the  heat  required 
to  change  a  unit  weight  of  a  solid  or  liquid  at  a  given 
temperature  into  a  gaseous  state  at  the  same  temper- 
ature. It  is  the  heat  that  disappears  during  the  change 
and  which  will  reappear  if  the  operation  is  reversed. 
Whereas  it  requires  only  180  B.t.u.  at  atmospheric 
pressure  to  heat  a  pound  of  water  from  the  freezing 
to  the  boiling  point  (termed  sensible  heat),  it  re- 
quires 970  B.t.u.  (latent  heat  of  evaporation)  to  con- 
vert the  same  quantity  of  water  into  steam  at  212  de- 
grees F. 


HEAT  ENERGY  AND  ELECTRICITY        5 

The  total  heat  of  evaporation  is  the  sum  of  the 
sensible  heat  and  the  latent  heat  of  evaporation. 

Radiation. — Heat  passes  from  warm  to  cold  bodies 
by  three  general  methods, — radiation,  conduction,  and 
convection.  Radiation  of  heat  takes  places  between 
bodies  at  all  distances  apart  and  the  heat  rays  pro- 
ceed in  straight  lines  until  intercepted  or  absorbed 
by  some  object.  The  amount  of  heat  transmitted 
varies  inversely  as  the  square  of  the  distance  from  the 
source.  The  rate  at  which  heat  is  given  off  or  absorbed 
depends  upon  the  character  of  the  surfaces  of  the 
bodies  as  well  as  upon  their  relative  temperatures. 
Dark  and  rough  surfaces  radiate  and  absorb  heat  more 
readily  than  smooth  and  polished  ones.  Radiant  heat 
passing  through  air  or  other  gases  does  not  affect 
their  temperature  to  any  appreciable  extent. 

Conduction. — The  transfer  of  heat  between  two 
bodies  or  parts  of  a  body  in  direct  contact  with  one 
another  is  termed  conduction.  It  differs  from  radiant 
heat  in  that  it  does  not  necessarily  travel  in  straight 
lines,  and  in  its  gradual  rather  than  instantaneous 
transfer.  The  quantity  of  heat  conducted  is  propor- 
tional to  the  cross  sectional  area,  to  the  temperature 
difference,  and  to  the  character  of  the  material. 

Metals  are,  in  general,  better  conductors  of  heat 
than  other  materials,  although  they  vary  to  a  very 
great  extent.  The  conducting  power  of  stone  is  less 
than  one  per  cent  that  of  copper,  and  iron  is  about 
3500  times  as  good  a  conductor  as  air. 

Convection. — The  transfer  and  diffusion  of  heat 
in  a  fluid  mass  through  the  motion  of  the  particles  of 
the  mass  is  termed  the  convection  of  heat.  The  parti- 
cles must  be  in  constant  motion  in  order  to  insure  uni- 
form temperature  of  the  mass.  When  the  particles 
come  into  contact  with  hot  bodies  the  mass  will  be 
warmed  in  proportion  to  the  freedom  of  circulation 
in  the  fluid. 

Air  is  usually  heated  in  a  room  by  circulation  of 
the  air  particles  and  bringing  them  into  contact  with 
heated   surfaces.     The   better   the   circulation    of    air 


6  ELECTRIC     HEATING 

against  these  surfaces  the  more  uniform  will  the  room 
temperature  become. 

Comparisons  of  Fuel  and  Electric  Heat. — The  rela- 
tive heating  values  of  fuels  are  often  compared  with 
electric  heat.  For  instance,  it  may  be  shown  that  with 
coal  having  a  heating  value  of  14,000  B.t.u.  per  pound 
and  costing  $5  per  ton,  manufactured  gas  having  a  heat- 
ing value  of  600  B.t.vi.  per  cu.  ft.  and  costing  $1  per 
thousand  cu.  ft.  and  electricity  having  a  heating  value 
of  3412  B.t.u.  per  kilowatt  hour  and  costing  one  cent 
per  kilowatt  hour,  one  cent  will  buy  56,000  B.t.u.  of 
coal  heat,  6000  B.t.u.  of  gas  heat,  and  3412  B.t.u.  of 
electric  heat.  However,  the  fact  must  not  be  over- 
looked that  all  fuel  apparatus  is  naturally  less  efficient 
than  electric  apparatus.  With  average  efficiencies  of 
say  10  per  cent  for  coal,  20  per  cent  for  gas,  and  70 
per  cent  for  electric  apparatus,  the  purchasing  power 
of  one  cent  under  the  above  assumed  prices  and  heat- 
ing values  would  be  5600  B.t.u.  of  coal  heat,  1200 
B.t.u.  of  gas  heat,  and  2388  B.t.u.  of  electric  heat. 

The  following  table  will  be  of  assistance  in  mak- 
ing hasty  comparisons  of  the  B.t.u.  value  of  fuel  and 
electric  heat.  Efficiencies  lower  than  50  per  cent  are 
seldom,  if  ever,  encountered  in  electric  applications 
and  are  therefore  omitted  from  the  table. 

B.t.ii.   PiiFfhasIng   Power    of   One    Cent. 

Efficiency   of  Apparatus 

in     <7^.: 100  75  50  30  20  10 

14,000  B.t.u.  Coal— 

$   5.00  per    ton 56,000   42,000   28,000   16,800   11,200   5,600 

$10.00  per    ton 28,000   21,000   14,000      8,400      5,600   2,800 

600    B.t.u.    Gas — 

$1.00  M.  cu.  ft 6,000  4,500   3,000   1,800  1,200   600 

$1.50  M.  cu.  ft 4,500   3,375   2,250  1,350    900   450 

Electricity — 

Ic  per  kw.-hr 3.412  2,559  1,706  

2c  per  kw.-hr 1,706  1,279  853  

3c  per  kw.-hr 1,137  853  568  

5c  per  kw.-hr 682  512  341  

Actual  experience  proves  that  many  careful  cal- 
culations do  not  work  out  in  practice.  One  might  as- 
sume from  the  above  figures,  for  instance,  that  the  cost 
of  using  a  gas  range  would  be  at  least  five  times  as 


LAMP     SOCKET     HEATING     DEVICES  9 

in  greater  quantities  than  any  other  electrically  heated 
device  known. 

The  principal  advantages  of  the  electric  iron  over 
the  old  fashioned  sad  iron  are  saving  in  time  and 
steps,  even  heat  distribution,  freedom  from  smoke, 
grease  and  soot,  absence  of  excessive  heat,  and  ease 
w^ith  which  it  may  be  used  in  any  part  of  the  house. 
Irons  varying  in  weight  from  3  pounds  to  9  pounds 
and  in  capacities  from  200  watts  to  675  watts  are  avail- 
able for  domestic  use. 

Electric  Stoves. — Both  the  disc  and  open  coil  type 
are  manufactured  in  various  sizes  and  capacities.  The 
disc  stove  has  a  metallic  heating  surface  and  delivers 


G.   E.   Twin   Plate   Disc   Stove. 

heat  to  the  utensil  by  conduction.  The  open  coil  stove 
gives  off  radiant  heat  from  exposed  coils  which  are 
usually  imbedded  in  grooves  of  porcelain  or  mounted 
above  metallic  reflectors. 

Electric  stoves  are  useful  for  many  household  pur- 
poses in  place  of  gas  or  alcohol  burners.  They  are 
suitable  for  heating  water  for  various  purposes,  or  for 
doing  light  cooking.  They  are  safe,  convenient  and 
durable.  For  domestic  lamp  socket  use  they  are  sel- 
dom larger  than  six  inches  in  diameter  and  600  watts 
in  capacity. 

Toaster  Stoves. — Two  distinct  types  are  made — 
horizontal  and  vertical.  Toast  made  on  the  horizontal 
type  will  be  produced  quickly  but  will  not  be  toasted 
through  so  well  unless  the  bread  be  dry.  Toast  made 
below  radiant  coils  or  in  the  vertical  type  toasters 
will  be  produced  slowly  but  will  be  toasted  thoroughly. 
Vertical  toasters  are  usually  provided  with  a  warm- 
ing shelf  on  top  to  keep  toast  or  other  food  warm. 


10 


ELECTRIC     HEATING 


Westinghouse    Horizontal    Toaster    Stove. 

One  great  advantage  of  electric  toasters  is  that 
they  may  be  used  on  the  dining  room  table  instead 
of  in  the  kitchen.  From  400  to  600  watts  are  usually 
required  for  operating  toasters. 


Hot  Point  Vertical  Toaster. 


Chafing  Dishes. — These  frequently  have  an  outer 
pan  in  addition  to  the  food  pan  for  use  as  double  boil- 
ers. The  food  pans  are  made  in  two  and  three-pint 
sizes.  The  capacities  vary  from  250  to  600  watts.  A 
wide  variety  of  styles  and  ornamental  types  are  avail- 
able. 

Electric  chafing  dishes  are  obviously  safer  to  op- 
erate than  alcohol  or  other  flame  types,  and  further- 
more they  give  oflf  no  disagreeable  odors  or  fumes. 


LAMP     SOCKET     HEATING     DEVICES 


11 


Universal  Chafing  Dish. 

Coffee  Percolators. — Coffee  made  in  an  electric 
percolator  is  rich  in  flavor,  free  from  grounds,  and 
contains  less  caffein  and  other  harmful  elements  than 
boiled  coffee.  Starting  with  cold  water,  strong  coffee 
may  be  prepared  in  from  ten  to  fifteen  minutes. 


Hot  Point  Percolator, 


Electric  percolators  in  all  styles,  shapes  and  char- 
acter of  ornamentation  and  in  sizes  varying  from  four 
to  nine  cups  are  available.  They  usually  require  from 
450  to  600  watts.    They  are  ideal  for  use  on  the  dining 


12 


ELECTRIC     HEATING 


room  table  because  they  are  attractive  in  appearance 
and  also  keep  the  coffee  hot  with  practically  no  atten- 
tion. 

Tea  Samovars. — The  housewife  who  prides  herself 
on  her  tea-making  is  pleased  with  a  device  where  the 
tea-ball  may  be  drawn  up  when  the  infusion  is  just 
right  and  a  beverage  served  of  fine  flavor,  and  free 
from  the  bitter  tannic  acid  taste  that  results  from 
1)oiling  tea-leaves  in  an  ordinary  pot.  It  is  especially 
desirable  for  the  afternoon  tea  because  it  can  be  oper- 
ated in  the  living  room.  It  furthermore  does  away 
with  the  disagreeable  odors,  fumes  and  dangers  of 
alcohol  or  other  fuel  types. 

Tea  samovars  are  usually  made  in  5,  6  and  7  cup 
sizes  and  in  capacities  varying  from  400  to  500  v/atts. 

Tea  Kettles. — Two  and  three  pint  sizes  are  usually 
made,  requiring  from  400  to  550  watts  for  operation. 
They  are  convenient  and  dainty  for  heating  water  for 
the  tea  service.  They  make  an  attractive  addition  to 
the  table  and  possess  the  charm  of  a  modern  household 
luxury. 


Simplex  Dining  Room  Set. 


Table  Cooking  Outfits. — Single  disc  stoves  sup- 
plied with  a  variety  of  hollow-ware  utensils  are  called 
unit-sets,  dining  room  sets  or  combination  stoves.  Cof- 
fee percolators,  tea  samovars,  chafing  dishes,  nursery 
milk  warmers,  frying  pans,  tea  kettles,  griddle  plates, 
and  other  utensils  are  included  in  the  various  sets. 

These  devices  bring  electric  cookery  within  reach 
of  every  one  and  encourage  a  better  understanding  of 


LAMP     SOCKET     HEATING     DEVICES  13 

its  cleanliness,  and  convenience.  For  the  hostess  who 
does  her  own  cooking  the  table  cooking  outfits  are 
ideal.  They  are  an  ornament  to  any  sideboard  or  table. 
Electric  Grills. — Many  handy  devices  for  cooking 
on  the  dining  room  table,  or  in  the  sick  room, 
and  which  are  attractive  and  convenient,  are  made 
by  various  heating  appliance  manufacturers.  The 
Hotpoint  El  Grillo  is  a  useful  table  device.     It  may 


%^ 


Hot   Point  Grill  Stove. 

be  used  for  light  toasting,  frying  and  broiling  as  well 
as  for  boiling.  Two  of  these  operations  may  be  carried 
on  at  one  time  as  the  utensils  may  be  placed  both 
above  and  below  the  glowing  coils.  It  has  a  capacity 
of  600  watts  and  the  dimensions  of  the  heating  element 
and  pans  are  4^4  by  8^  inches. 

The  Westinghouse  toaster  stove  is  really  a  small 
complete  cook  stove.  It  may  be  used  for  broiling, 
frying,  toasting,  boiling  or  making  griddle  cakes.  The 
stove  is  5%  by  9  by  3^  in.  high  and  consumes  500 
watts. 

The  General  Electric  radiant  grill  may  be  used 
for  frying,  stewing,  toasting,  and  broiling.  This  device 
consumes  600  watts. 

Food  Warmers. — Eood  warmers  are  made  in  a 
variety  of  portable  styles,  shapes,  and  sizes,  and  may 
be  used  on  the  table  or  sideboard. 

Simplex  nickel  or  silver  plated  food  warmers  of 
the  following  sizes  and  capacities  are  available : 

Oval  shape,  10  in.  by  14  in 170  watts 

Oblong  shape, 

10   in.   by    14   in 200 

10    in   by    18    in 250 

Oblong-  shape  (extra  heavy) 

10   in.   by   14   in 200 

10   in.   by   18   in 250 

10   in.   by  26   in 400 


14 


ELECTRIC     HEATING 


Simplex   Food  Warmer. 


Plate  Warmers  and  Hot  Closets. — A  variety  of 
shapes  and  sizes  of  plate  warmers  and  hot  closets  are 
manufactured  to  order  to  fit  available  spaces,  or  stand- 
ard portable  types  may  be  used. 


Hughes   Plate  Warmer 


In  estimating-  the  size  of  a  plate  warmer  closet  a 
shelf  space  of  at  least  10>^  in.  should  be  allowed  for 
ordinary  dinner  plates  and  a  height  of  6  in.  for  twelve 
in  a  pile. 

On  account  of  the  relatively  low  temperature  re- 
quired inside  the  oven,  the  current  consumption  is 
usually  low,  especially  if  the  walls  are  well  insulated 
against  heat  losses. 

Bake  Ovens. — Devices  like  the  small  Hotpoint 
lamp  socket  bake  ovens  (El  Bakos)  are  useful  for  light 


LAMP     SOCKET     HEATING     DEVICES  15 

baking  operations.  The  inside  dimensions  are  11  in.  by 
10y2  in.  by  7y2  in.  and  they  consume  600  watts  on  the 
high  heat.     They  are  of  steel  construction  with  nickel 


Hot  Point  El  Bako. 


trimmings  and  the  walls  are  lined  with  mineral  wool 
to  retain  the  heat.  These  ovens  have  practically  all 
the  inherent  advantages  of  larger  electric  ovens. 


Simplex    Nursery    Milk   Warmer. 


Nursery  Milk  Warmers. — These  consist  of  a  water 
vessel  and  cover,  a  milk  bottle,  and  a  nipple.  They  are 
designed  for  quick  heating  and  are  made  in  capacities 
varying  from  300  to  500  watts.  They  are  ready  for 
use  at  any   time — day  or  night.     The  500  watt  size 


16 


ELECTRIC     HEATING 


will  heat  a  bottle  of  milk  in  about  four  minutes  or 
boil  a  pint  of  water  in  about  six  minutes. 

Curling  Iron  Heaters. — These  are  desirable  on  ac- 
count of  their  absolute  cleanliness,  convenience,  and 
safety.     They   are    made   in    capacities    varying   from 


Universal  Curling  Iron  and  Hair  Dryer. 

60  to  90  watts  and  in  plain  or  ornamental  types.  The 
Westinghouse  electric  curling  iron  is  equipped  with 
a  heating  element  inside  the  iron  which  consumes 
15  watts. 

Warming  Pads. — For  local  applications  of  heat 
to  the  body  electric  pads  are  rapidly  superseding  the 
hot  water  bottle  and  similar  devices.     These  pads  are 


Simplex  Warming  Pad. 

usually  made  of  soft  padded  cloth  although  some  of 
the  new  Hotpoint  pads  are  made  of  either  rigid  or 
flexible  metallic  materials.  The  Westinghouse  pads 
are  11  in.  by  15  in.  and  have  an  outer  rubber  cover. 
The  Simplex  pads  have  an  eiderdown  cover  and  are 
made  in  two  sizes,  12  in.  by  15  in.  and  15  in.  by  24  in. 


LAMP     SOCKET     HEATING     DEVICES  17 

The  American  warming  pad  is  12  in.  by  13  in.  Warm- 
ing pads  are  generally  provided  with  regulating 
switches  giving  three  degrees  of  heat.  The  capacities 
vary  according  to  dimensions  from  50  to  100  watts 
maximum.  The  American  sweating  blanket  is  5  ft. 
long  by  18  in.  wide  and  requires  800  watts. 

Immersion  Heaters. — These  appliances  are  useful 
in  the  home  that  is  not  provided  with  a  constant  supply 
of  hot  water.  By  fastening  to  the  lamp  socket  and  sub- 
merging the  heater  in  water  or  other  liquid  the  sub- 


Hot  Point  Immersion  Heateis. 

Stance  can  be  brought  to  a  boil  very  quickly.  Inas- 
much as  the  heating  element  is  placed  directly  in 
the  liquid  the  efficiency  of  operation  is  high.  They 
are  handy  for  shaving  and  similar  purposes.  Heaters 
of  various  shapes  and  capacities  are  available. 

Other  Household  Devices. — A  few  of  the  better 
known  heating  and  cooking  devices  are  mentioned  for 
reference  purposes. 

Egg  boilers  are  convenient  because  they  can  be 
used  on  the  table  and  given  personal  supervision. 

Fry  pans  and  saute  pans  designed  for  use  on  the 
dining  room  table  are  useful. 

Soup  tureens  are  handy  for  keeping  soups  and 
other  prepared  foods  at  the  proper  temperature  for 
serving. 


18  ELECTRIC     HEATING 

The  Hotpoint  utility  outfit  which  comprises  a 
three  pound  iron  provided  with  a  stand  on  which  it 
may  be  inverted  for  cooking,  and  a  receptacle  for  in- 
serting a  curling  iron  is  useful  for  the  roomer  or  trav- 
eler. 

The  foot  warmer  is  a  handy  device  for  use  in 
rooms   with   cold   floors.     If  placed   under  a  desk   or 


Universal  Egg  Cooker 

table  it  will  keep  an  occupant  warm  even  when  the 
room  is  comparatively  cold. 

Air  radiators  of  both  the  radiant  and  convection 
types  are  useful  in  small  rooms  and  in  cold  corners. 
A  separate  chapter  is,  however,  devoted  to  the  sub- 
ject of  air  heating. 


CHAPTER  III 

INSTALLATION  OF  HEATING  APPARATUS. 

Correct  Installation. — This  is  essential  for  ranges, 
water  heaters,  and  other  heating  devices.  If  wires  are 
too  small,  the  service  will  be  poor.  If  the  appearance 
of  the  work  is  not  good,  the  user  will  be  dissatisfied. 
If  proper  protection  against  electric  shocks  is  not 
aflForded,  the  customer  may  be  in  constant  fear.  If 
a  range,  for  instance,  is  not  placed  in  such  a  position 
that  it  can  be  conveniently  operated  by  the  cook  or 
housewife,  she  may  form  mental  prejudices  that  will 
be  difficult  to  overcome.  Intelligent  supervision  and 
caretul  inspection  of  all  heating  installations  will  be  of 
mutual  benefit  to  all  concerned. 

Wiring  for  Heating  Apparatus. — The  Code  of  the 
National  Board  of  Fire  Underwriters  should  be  adhered 
to  as  closely  as  possible  in  wiring  for  heating 
apparatus.  Furthermore,  local  city  and  state  rulings 
have  a  distinct  legal  status  the  importance  of  which 
should  not  be  overlooked.  Unfortunately  the  National 
Code  rulings  which  apply  to  the  installation  of  heat- 
ing service  are  in  some  cases  burdensome,  and  in 
others  not  strict  enough. 

All  wiring  should  be  done  in  a  neat  and  work- 
manlike manner  so  that  an  electric  installation  will  not 
detract  in  any  way  from  the  appearance  of  the  prem- 
ises. Electric  ranges,  water  heaters,  and  other  heat- 
ing devices  on  the  market  usually  look  attractive,  but 
if  they  are  not  properly  connected  and  installed  the 
general  appearance  may  be  bad. 

Carrying  Capacities  of  Wires. — The  allowable  car- 
rying capacity  of  conductors  operating  under  pres- 
sures of  120  volts,  two-wire,  and  120-240  volts,  three- 
wire,  are  given  in  Table  I  for  convenient  reference 


20 


ELECTRIC     HEATING 


Table   I. 

Maximum  Allowable  Wattage  Carrying  Capacity. 


Size 

Area 

— Rubber 

Covered — 

— Weather  Proof— 

B.  &S. 

Circ. 

120  volt. 

120-240  V. 

120  volt 

120-240  V. 

Gauge. 

Mils. 

2-wire. 

3-wire. 

2-wire. 

3-wire. 

0000 

211,600 

27,000 

54.000 

39,000 

78,000 

000 

167,800 

21,000 

42,000 

33,000 

66,000 

00 

133,100 

18,000 

36,000 

27,000 

54.000 

0 

105,500 

15,000 

30,000 

24,000 

48,000 

1 

83,690 

12,000 

24,000 

18,000 

36,000 

2 

66,370 

10,800 

21,600 

15,000 

30,000 

4 

41,740 

8,400 

16,800 

10,800 

21,600 

6 

26,250 

6,000 

12,000 

8,400 

16.800 

8 

16,500 

4,200 

8,400 

6,000 

12.000 

10 

10,380 

3,000 

6,000 

3,600 

7,200 

12 

6,530 

2,400 

4,800 

3,000 

6,000 

Wires  of  sufficient  size  to  conform  to  the  allow- 
able carrying  capacities  in  the  above  table  will  conform 
to  the  Underwriters'  Code  but  may  prove  too  small 
to  insure  good  service.  This  will  be  true  if  the  run 
is  a  long  one  because  in  the  above  table  no  account  is 
taken  of  its  length. 

Table  II  shows  the  drop  in  voltage  (below  120) 
that  may  be  figured  per  hundred  feet  of  both  two  and 
three-wire  circuits.  The  calculations  are  based  on 
an  assumed  pressure  of  120  volts  for  two-wire  service 
and  120-240  volts  impressed  on  a  three-wire  circuit. 

Table   II. 

Wattage  Load  on  End  of  Line. 


No. 

2500 

5000 

7500 

B.  &S. 

2- 

3- 

2- 

3- 

2- 

3- 

Gauge 

wire. 

wire. 

wire. 

wire. 

wire. 

wire. 

OiQCO 

.204 

.102 

.409 

.204 

.619 

.306 

000 

.258 

.129 

.515 

.258 

.774 

.386 

00 

.325 

.162 

.650 

.325 

.975 

.487 

0 

.410 

.205 

.819 

.410 

1.229 

.615 

1 

.517 

.258 

1.033 

.417 

1.550 

.775 

2 

.651 

.326 

1.303 

.651 

1.954 

.977 

4 

1.036 

.518 

2.071 

1.036 

3.107 

1.553 

6 

1.647 

.824 

3.294 

1.647 

4.941 

2.471 

8 

2.618 

1.309 

5.237 

2.618 

7.855 

3.927 

10 

4.164 

2.082 

8.329 

4.164 

6.246 

12 

6.623 

3.312 

6.623 



9.935 

No. 

10,000 

15,000 

25,000 

B.  &S. 

2- 

3- 

2- 

3- 

2- 

3- 

Gauge 

wire. 

wire. 

wire. 

wire. 

wlre. 

wire. 

0000 

.818- 

.409 

1.238 

.619 

2.044 

1.022 

000 

1.03i0 

.515 

1.548 

.774 

2.576 

1.288 

00 

1.200 

.650 

1.950 

.975 

3.250 

1.625 

0 

1.638 

.819 

2.458 

1.229 

4.096 

2.048 

1 

2.066 

1.033 

3.100 

1.550 

5.166 

2.582 

2 

2.606 

1.303 

3.908 

1.954 

6.515 

3.257 

4 

4.143 

2.071 

6.214 

3.107 

5.178 

6 

6.588 

3.294 

9.882 

4.941 

8.235 

8 

5.237 

7.855 

.... 

10 

8.329 

.... 

12 

.... 

.... 

INSTALLATION     OF     HEATING     APPARATUS         21 

Correct  Voltage. — For  heating  apparatus  this  is 
important.  Many  complaints  may  be  obviated  by  sup- 
plying energy  at  a  pressure  as  near  as  possible  to  the 
rated  voltage  of  the  apparatus.  Low  voltage  results 
in  slowness  of  operation,  and  excessively  high  volt- 
age is  likely  to  cause  burn  outs. 

Assume  a  heating  element  rated  at  1100  watts 
and  110  volts  is  supplied  with  energy  at  a  pressure  of 
100  volts.  The  resistance  of  the  element  is  therefore: 
R  =E/I  =  110/10=11  ohms. 

At  100  volts  pressure  the  quantity  of  current  flow- 
ing would  be  I  ^  E/R  ^  110/11  ^  9.1  amperes  and 
the  wattage  dissipated  in  heat  would  be  W  =  EI  = 
9.1X100^910  watts.  The  efficiency  of  operation 
of  the  element,  therefore,  would  be  910/1100  =  82.7 
per  cent,  whereas  the  voltage  was  supplied  at  only 
100/110  =  91   per  cent  of  the  normal  rating. 

Voltage  readings  should  always  be  made  at  the 
terminals  of  the  heating  device  at  no  load  and  at  full 
load,  otherwise  the  drop  in  voltage  in  the  service 
leads  or  interior  wiring  may  be  overlooked,  and  a 
wrong  impression  gained. 

Methods  of  Wiring. — How  to  wire  a  building  for 
heating  service  should  be  carefully  considered  before 
the  actual  work  is  undertaken.  Exposed  wiring  with 
knobs  and  cleats  is  safe  and  cheap  but  is  seldom  used 
because  of  its  unsightliness.  Moulding  work  is  some- 
times installed  in  old  buildings  but  unless  the  work 
is  done  extremely  well  it  may  look  unattractive.  The 
concealed  knob  and  tube  method  is  often  used  in  both 
new  and  old  buildings  and  the  work  may  usually  be 
done  at  reasonable  cost.  Rigid  or  flexible  conduit,  or 
steel  armored  conductor  wiring  are  generally  consid- 
ered to  be  the  best,  although  the  most  expensive 
methods. 

Exposed  Knob  and  Cleat  Wiring. — This  is  often 
used  in  wiring  for  heating  and  cooking  service  and  in 
places  where  appearance  is  of  little  consequence  it  is 
one  of  the  cheapest  and  best.  The  wires  may  be  single 
braid  rubber-covered  or  slow  burning  weather-proof. 


22  ELECTRIC     HEATING 

In  cellars  or  other  places  exposed  to  moisture  rubber- 
covered  wire  must  be  used. 

Wooden  Moulding  Wiring. — Where  a  neat  ap- 
pearing low-priced  job  is  required  this  construction 
may  well  be  used.  Its  use  in  damp  places  is  however 
prohibited  by  the  Underwriters.  Single  braid  rubber- 
covered  wire  is  required.  For  first  class  work  hard 
wood  moulding,  matching  in  finish  the  trim  of  the 
room,  can  be  used. 

Wiring  in  Metal  Moulding. — As  this  is  restricted 
to  circuits  carrying  not  more  than  1320  watts  it  is 
seldom  employed  for  heating  or  cooking  circuits. 
Single  braid  rubber-covered  wire  may  be  used  for  this 
class  of  work.  Metal  moulding  must  always  be 
grounded  permanently. 

Concealed  Knob  and  Tube  Wiring. — In  frame 
buildings  where  a  low  cost  of  installation  is  essential 
the  wires  may  be  installed  within  floors  and  partitions. 
Wires  can  ordinarily  be  concealed  in  this  manner 
more  cheaply  than  by  any  other  method.  Single  braid 
rubber-covered  wire  may  be  used. 

Rigid  Iron  Conduit. — This  is  approved  for  both 
exposed  and  concealed  work.  Ordinarily  it  is  prob- 
ably the  best,  although  the  most  expensive.  Double 
braid,  rubber-covered  wire  must  be  used  in  rigid 
conduit.  The  same  conduit  may  contain  as  many  as 
4  two-wire  or  3  three-wire  circuits.  Stranded  wire 
in  sizes  larger  than  No.  6  is  customarily  used  for  rigid 
conduit   work.      Rigid   conduit   must   be   permanently 


grounded. 

Table  III. 

Size  of 

Size 

of  Conduit,  Inches. 

Wire. 

Two 

Wires  in  Conduit.       Three 

Wires   in 

Conduit. 

B.  &S. 

Short 

Medium 

Long-         Short 

Medium 

Long 

Gauge. 

Run. 

Run. 

Run.            Run. 

Run. 

Run. 

10 

V2 

% 

%                 % 

1 

1 

8 

% 

% 

1                  1 

IV4 

ly* 

6 

1 

1 

1^              1 

iy4 

1% 

4 

1 

1% 

1^              IV4 

iy4 

1V2 

2 

1% 

1% 

1%              1% 

1V2 

2 

1 

IV* 

1% 

'     2                   IV2. 

2 

2 

0 

1% 

2 

2                   2 

2 

2 

00 

1% 

2 

2                   2 

2 

2y2 

000 

2 

2 

2                   2 

2y2 

2y2 

0000 

2 

2 

2%               2 

2y2 

3 

INSTALLATION     OF     HEATING     APPARATUS         23 

Table  III  shows  the  size  of  double  braid  rub- 
ber-covered wires  that  can  readily  be  pulled  into  con- 
duit. 

Flexible  Metallic  Conduit. — For  all  kinds  of  ex- 
posed or  concealed  work  such  construction  is  often 
preferable  to  rigid  conduit.  The  installation  of  flexible 
conduit  can  be  made  easier,  quicker,  and  more  cheapl}^ 
than  can  riged  conduit.  The  same  code  rules  apply  to 
flexible  as  to  rigid  conduit.  It  must  be  securely 
grounded.  Double  braid  rubber  covered  wire  is  re- 
quired. Flexible  metallic  conduit  may  be  used  to  ad- 
vantage in  finished  houses  and  in  frame  buildings. 

The  sizes  of  wire  that  may  be  accommodated  in 
flexible  steel  conduits  are  given  in  table  IV. 


Nominal 

Table 

IV. 

aside   Diam. 

Largest 

Wires 

Accomm( 

adated. 

In  Inches. 

o 

ne  Wire. 

Two  W 

ires. 

Three  Wires. 

y2 
% 

1 

ly* 

IVs 
2 

8 

2 

00 

200,000 

400,000 

800,000 

12 

10 

0 

4 

1 
200,000 

12 
8 
6 
3 

00 

Flexible  Steel  Armored  Conductor. — Here  a  cable 
consisting  of  rubber-covered  wires  is  protected  from 
injury  and  to  a  certain  extent  from  dampness  by  two 
layers  of  flexible  steel  armor.  It  may  be  obtained 
leaded  or  unleaded.  The  leaded  cable  diflfers  from  the 
unleaded  in  that  it  has  a  lead  covering  between  the  wire 
and  the  steel  armor  to  protect  it  from  excessive  damp- 
ness. Both  the  leaded  and  the  unleaded  cables  are  made 
with  single  and  multiple  conductors  of  almost  any 
gauge  wire.  The  leaded  cable  is  approved  for  all 
classes  of  work,  open  or  concealed,  in  fireproof  or  non- 
fireproof  buildings,  and  in  new  or  old  houses.  The  un- 
leaded cable  is  approved  and  may  be  used  for  open 
or  concealed  work  in  places  not  subject  to  moisture. 

For  wiring  old  buildings  steel  armored  con- 
ductor can  be  used  to  great  advantage.  It  can  be 
run  with  utter  disregard  to  contact  with  pipes  or  other 
materials  and  may  be  fished  for  long  distances.  It 
can  be  installed  quicker  and  with  less  cutting  away 
of  the  walls  and  floors  than  either  rigid  conduit,  flex- 


24  ELECTRIC     HEATING 

ible  tubing,  or  concealed  knob  and  tube  work.  Steel 
armored  conductor  should  always  be  carefully 
grounded. 

The  Main  Entrance  Switch. — For  three-wire  heat- 
ing circuits  this  should  always  be  of  the  fused  type 
with  the  neutral  fuse  coppered. 

Control  Switch. — Heating  devices  should  be  pro- 
vided with  control  switches  that  will  indicate  at  a  glance 
whether  the  circuit  is  open  or  closed.  The  switch 
should  be  mounted  on  the  device  or  on  the  wall  imme- 
diately adjacent  to  it  so  as  to  be  easily  accessible.  It 
should  be  of  the  enclosed  knife  blade  or  snap  switch 
type  and  so  designed  as  to  entirely  disconnect  the  heat- 
type  appliance  at  the  wish  of  the  operator. 

Grounding. — The  frames  of  all  heating  appliances, 
especially  those  of  the  larger  types,  should  be  carefully 
grounded,  whether  they  are  connected  to  two-wire  or 
three-wire  circuits.  Satisfactory  grounding  may  be 
accomplished  by  connecting  the  frame  of  the  device  to 
a  water  pipe.  If  the  appliance  is  operated  from  a  three- 
wire  grounded  neutral  system  the  frame  may  be  con- 
nected to  the  neutral  wire.  In  case  of  doubt  as  to  the 
character  of  the  ground  on  such  a  system,  the  neutral 
may  be  grounded,  in  turn,  to  some  convenient  water 
pipe  inside  the  building. 

When  a  rigid  or  flexible  metallic  conduit  or  steel 
armored  conductor  job  is  installed,  the  frame  of  the 
device  may  be  grounded  to  the  conduit  or  steel  armor ; 
provided,  of  course,  the  conduit  or  armor  is  itself 
grounded  elsewhere. 

Ranges  in  Apartment  Houses  and  Flats. — In  this 
case  separate  circuits  from  the  main  switchboard  are 
necessary.  Each  circuit  must  be  fused  but  in  the  case 
of  three-wire  circuits  the  neutral  should  be  coppered. 

Main  service  wires  and  switches  supplying  group 
cooking  loads  are  never  called  upon  to  carry  the  entire 
connected  load.  Apartment  houses  equipped  with 
ten  or  more  ranges  are  never  known  to  have  a  demand 
greater  than  one-fourth  the  connected  load.  The 
larger  the  number  of  ranges  supplied  from  a  single 


INSTALLATION     OF     HEATING     APPARATUS         25 

service  the  less  will  be  the  demand  in  proportion  to 
the  load  connected.  This  is  a  condition  seldom  met 
with  in  supplying  other  classes  of  electric  service  and 
one  for  which  no  provision  has  been  made  in  the  Un- 
derwriters' Code.  It  is  obvious,  however,  that  to 
install  service  leads,  main  switches,  fuses,  etc.,  of 
sufficient  carrying  capacity  to  handle  the  total  con- 
nected load  would  be  of  no  advantage,  and  would  in- 
volve needless  expense. 

The  Proper  Position  for  a  Range. — The  range  should 
be  located  where  it  can  be  operated  with  ease  and  conven- 
ience. If  it  is  placed  where  the  light  is  bad,  in  an  inac- 
cessible corner  of  the  kitchen,  or  where  the  cook  or 
housewife  has  to  walk  back  and  forth  a  greater  distance 
than  that  to  which  she  has  been  accustomed,  a  serious 
prejudice  may  be  created  in  her  mind.  An  electric 
range  is  often  installed  in  a  kitchen  by  the  side  of 
a  coal,  gas,  wood,  or  oil  range,  the  latter  being  left 
in,  either  for  auxiliary  use  or  for  want  of  a  better 
place  for  storing  the  old  equipment.  When  this  con- 
dition is  met,  every  endeavor  should  be  made  to  secure 
permission  to  place  the  electric  range  in  the  most 
advantageous  position.  Otherwise  the  customer  will 
have  a  tendency  to  use  the  appliance  most  favorably 
located  for  most  of  her  work. 


CHAPTER  IV 

ELECTRIC  COOKING. 

The  March  of  Progress. — Modern  civilization's  ad- 
vance may  be  clearly  indicated  by  the  progress  in 
methods  of  cooking.  Wood  was  the  first  material  to 
be  used  as  a  fuel.  Water  was  boiled  in  a  kettle  sus- 
pended over  a  log  fire  and  meats  were  broiled  on  a 
spit,  or  roasted  in  the  embers,  for  many  hundreds  of 
years.  When  it  was  found  that  coal  produced  a  more 
uniform  and  hotter  fire,  and  was  far  more  desirable 
than  wood,  another  era  of  progress  was  marked.  The 
old  fashioned  fire  place  gave  way  to  the  more  modern 
kitchen  range.  Then  came  fuel  gas,  which  may  be 
considered  a  product  of  coal,  and  the  gas  stove  made 
its  appearance.  Although  the  use  of  gas  obviously  in- 
volved more  danger  and  was  somewhat  more  expen- 
sive, it  was  found  to  be  quicker  and  far  more  con- 
venient. 

Crowning  success  was  achieved,  however,  when 
the  electric  method  was  perfected,  and  the  bridging 
of  space  between  the  historic  fuel  fire  and  the  modern 
heat  produced  without  flame  was  accomplished. 

Advantages  of  Electric  Cooking. — The  extent  of 
the  improvement  brought  about  by  the  electric  range 
is  almost  unbelievable.  The  heat  is  under  absolute 
control.  The  operator  knows  and  commands  the  tem- 
perature at  all  times.  The  wasting  of  heat  has  been 
reduced  to  a  minimum.  The  units  or  burners  generate 
the  heat  right  where  it  is  used,  and  very  little  loss  takes 
place.  The  heat  utilized  in  the  oven  is  generated  on 
the  inside,  and  as  its  walls  are  heavily  insulated  with 
material  of  low  thermal  conductivity,  there  is  prac- 
tically no  opportunity  for  useful  energy  to  escape. 

Facility  of  Operation. — The  electric  range  is  easier 
to  operate  and  can  be  regulated  with  a  much  greater 
degree  of  accuracy  and  certainty  than  the  fuel  range. 


ELECTRIC    COOK] 


27 


Being  clean,  safe  and  labor-saving,  its  use  promotes 
greater  cleanliness  and  comfort.  It  produces  no  excess 
heat,  smoke  or  fumes  to  vitiate  the  atmosphere,  and 
does  away  with  the  constant  attention  and  anxiety  of 
the  fuel  fire.  Cooking  utensils,  furthermore,  may 
always  be  kept  clean  and  free  from  smoke  and  soot 
on  both  the  inside  and  outside. 


Hughes  No.  60  Range  (for  Large  FamUy  Use). 


Uniformity  is  attained  in  the  electric  range  be- 
cause it  will  always  produce  the  same  results  under 
the  same  operating  conditions.  For  instance,  the  oven 
has  to  be  opened  but  twice  for  each  operation — once 
when  the  food  is  inserted,  and  again  when  the  cooking 
is  completed.  The  operator  has  only  to  watch  the 
clock  while  the  food  is  cooking.  This  advantage  par- 
tially removes  the  objection  that  many  persons  have 
to  a  low  oven,  which,  with  fuel  stoves,  requires  con- 
stant bending  over  to  examine   the   condition   of  the 


28  ELECTRIC    HEATING 

food.  Any  housewife,  of  even  moderate  intelligence, 
should  be  able  to  master  the  essential  features  of  the 
operation  of  an  electric  range  in  a  short  time  by  simply 
reading  the  card  of  instructions  that  is  sent  out  by  the 
manufacturers  with  each  range. 

Special  Advantages. — The  individual  operations  in 
which  the  electric  range  outclasses  every  known  type 
of  fuel  stove,  are  baking,  roasting  and  broiling.  The 
heat  being  uniformly  distributed  in  all  parts  of  the 
oven,  insures  even  baking  and  browning.  It  will  bake 
bread,  cake,  and  pies  that  are  most  attractive  in  ap- 
pearance. They  will  always  have  just  the  right  color, 
will  contain  more  nourishment,  and  remain  fresh 
longer.  Roasts  should  always  be  prepared  in  an  open 
pan  containing  no  moisture,  and  basting  is  unnecessary 
in  the  electric  oven.  Sufficient  moisture  and  meat 
greases  will  collect  in  the  pan  during  the  operation  to 
prevent  burning,  and  to  provide  material  for  gravy. 
The  roast  itself  will  come  out  of  the  oven  uniformly 
browned  on  top,  bottom  and  sides,  if  no  basting  is  done. 
In  both  roasting  and  broiling  operations  the  meat  is 
seared,  thereby  retaining  its  natural  juices,  and  mak- 
ing it  more  delicious,  nutritious  and  attractive  to 
serve. 

Reduction  in  Meat  Shrinkage. — Many  experiments 
have  been  made  in  actual  practice  to  show  that  there 
is  less  shrinkage  in  meats  prepared  electrically  than 
by  any  other  means.  The  meats  sear  over  as  soon  as 
placed  in  the  oven ;  there  is  no  burning  away  of  the 
fats  and  juices;  and  a  saving  of  from  15  per  cent  to 
18  per  cent  in  the  actual  weights  of  the  meats  is 
efifected.  The  tremendous  economy  in  household  ex- 
pense that  is  made  possible  by  the  use  of  the  electric 
range  is  apparent  if  we  consider  a  family  whose  meat 
bill  has  averaged  $15  per  month  and  a  saving  made  of 
15  per  cent  in  the  meat  shrinkage  by  the  use  of  elec- 
tricity. Meat  costs  in  this  family  would  be  reduced 
$2.25  per  month  with  the  exercise  of  no  additional 
self  denial. 

Assume  an  eight  pound  roast  is  placed  in  a  1600 
watt  electric  oven  and  roasted  IVi  hours.    The  current 


ELECTRIC    COOKING  29 

consumption  at  high  heat  would  be  4  kilowatt  hours, 
but  by  proper  manipulation  of  the  oven  switch  not 
over  half  this  amount,  or  2  kilowatt  hours,  would  be 
actually  consumed.  The  saving  in  weight  of  the  meat 
over  gas  or  coal  cooking  would  amount  to  at  least 
one  pound.  With  current  costing  three  cents  per  kilo- 
watt hour  and  meat  twenty  cents  per  pound  the 
actual  saving  to  the  housewife  in  cooking  the  roast 
electrically  would  be  as  follows : 

1  lb.  of  meat  saved  at  20c $  .20 

2  kw  -hr.  at  3c  cost 06 

Actual  saving   $0.14 


Model  G  Hot  Point  Range.  Simplex  5-K  Range. 

Important  to  Use  Proper  Utensils. — Only  flat  bot- 
tomed utensils  should  be  used  for  surface  cooking  on 
the  electric  range.  Air  is  a  poor  conductor  of  heat, 
and  consequently,  the  closer  the  heating  unit  can  be 
brought  to  the  bottom  of  the  utensil,  the  greater  will 
be  the  efficiency  of  operation.  The  necessity  is  par- 
ticularly apparent  in  ranges  making  use  of  an  element 
of  the  enclosed  type,  where  the  heat  is  transmitted  to 
the  food  from  a  hot  surface  through  the  bottom  of  a 
utensil.  If  direct  metallic  contact  is  not  secured  the 
efficiency  will  be  tremendously  impaired ;  slow  opera- 
tion will  result ;  and  the  housewife  will  become  dis- 
pleased. 

Agate  or  enameled  ware  should  never  be  used  on 
enclosed  type  elements.     Iron,   copper,  or  aluminum 


30  ELECTRIC    HEATING 

vessels  will  be  found  far  more  efficient.  On  the  other 
hand,  agate,  enameled  ware,  and  black  bottomed  iron 
utensils  have  been  found  very  satisfactory  for  use  with 
open  type  elements.  Polished  metallic  bottom  sur- 
faces reflect  and  do  not  take  up  the  heat  from  a  ra- 
diant type  element  as  do  black  surfaces.  Contrary- 
wise,  highly  polished  sides  and  tops  retain  heat  in  a 
utensil  much  more  efficiently  than  do  dark  or  rough 
surfaces.  If  the  bottom  of  any  kind  of  utensil  is  cor- 
rugated, hollowed  out  or  warped  it  cannot  be  ex- 
pected to  give  satisfactory  results. 

Economy  in  Range  Operation. — Food  prepared  on 
the  cooking  surface  will  not  burn  on  the  inside  of 
the  utensil  as  long  as  any  moisture  remains  in  the  ves- 
sel, because  heat  is  applied  only  at  the  bottom  and 
never  at  the  sides.  For  this  reason,  the  amount  of 
water  usually  required  to  keep  food  from  burning  may 
be  reduced  and  the  operations  performed  more  easily 
and  quickty.  The  food  will  be  steamed  thoroughly,  and 
the  natural  sweetness  and  flavor  will  be  cooked  into 
the  food,  rather  than  boiled  out  into  the  water  poured 
away.  Water  absorbs  more  heat  than  any  commonly 
known  substance,  and  a  little  economy  in  the  use  of 
water  will  effect  considerable  saving  in  both  heat  and 
electricity. 

Users  of  electric  ranges  should  be  encouraged  to 
use  water  drawn  from  the  hot  water  storage  supply  for 
cooking  purposes.  Water  taken  from  the  top  of  a 
tank  is  obviously  purer  than  that  taken  from  the  water 
mains  because  the  tank  acts  as  a  natural  settling 
basin  for  the  collection  of  all  impurities  and  sediment. 
If  hot  water  is  used  in  preparing  foods,  the  operations 
may  be  done  more  quickly,  and  considerable  saving  in 
current  consumption  effected. 

One  very  common  method  of  effecting  economies 
in  the  operation  of  a  range,  is  to  place  as  many  foods 
as  possible  in  the  oven  instead  of  on  the  cooking  sur- 
face. The  oven,  being  heavily  insulated,  retains  prac- 
tically all  the  heat  generated  and  the  usual  losses  that 
attend  cooking  on  the  surface  units  are  thereby  done 
away  with. 


ELECTRIC    COOKING 


31 


Water  for  laundry  work,  washing,  bathing,  and 
other  domestic  purposes  cannot  be  heated  as  econom- 
ically on  an  electric  range  surface  as  by  other  means. 
If  the  housewife  desires,  however,  she  may  success- 
fully boil  clothes  by  placing  an  ordinary  copper  bot- 


Hughes   Junior   Range    (for   Early   Training   of   Housewife). 


tom  boiler  over  two  of  the  range  discs.  Quicker  ac- 
tion will  result  if  the  boiler  is  kept  covered,  and  a 
heavy  paper  wrapped  about  the  sides  of  the  vessel. 

The  saving  that  may  be  effected  by  skilful  use  of 
the  individual  three-heat  switches  is  often  little  under- 
stood by  the  average  woman.  She  should  be  trained 
to  know  that  the  low  heat  consumes  but  one-quarter, 
and  the  medium  heat  one-half  as  much  current,  as 
the  high  heat.  Food  brought  to  the  boiling  point  on 
high  heat  should  be  retained  at  this  temperature  at 


32  ELECTRIC    HEATING 

low  or  medium  heat.  A  boiling  temperature  higher 
than  212  degrees  F.  cannot  be  obtained  in  an  open 
vessel  and  food  will  cook  just  as  quickly  when  boiling 
slowly  as  when  boiling  rapidly. 

Elimination  of  Kitchen  Chimneys. — If  fuel  is 
burned  in  a  kitchen  a  chimney  is  naturally  required. 
On  the  other  hand  the  expense  of  installing  a  chimney 
may  be  obviated  by  using  an  electric  range.  Even 
with  gas  the  harmful  products  of  combustion  must  be 
removed  as  shown  by  the  following  from  page  20, 
Technical  Paper  109,  U.  S.  Bureau  of  Mines  : 

"Natural  gas,  when  burned  with  sufficient  oxygen  for 
complete  combustion,  forms  carbon  dioxide  and  water  vapor. 
Each  cubic  foot  of  natural  gas  burned  produces  a  little  over 
1  cubic  foot  of  carbon  dioxide  and  a  little  more  than  2  cubic 
feet  of  water  vapor.  Carbon  dioxide  is  an  irrespirable  gas  and 
should  not  be  allowed  to  accumulate  in  a  room.  Water  vapor 
also  should  be  removed,  because  it  has  a  depressing  effect 
if  present  in  still,  warm  air  in  sufficient  proportion  and  tends 
to  make  the  walls,  ceilings,  curtains  and  other  objects  in  a 
room  dirty  because  the  dust  is  entrained  iby  it  and  settles  on 
the  objects." 

"The  only  way  to  remove  these  two  gases  is  by  means 
of  a  vent  leading  from  the  stove  to  the  house  chimney.  It  is 
absurd  for  any  manufacturer  of  stoves  to  claim  that  these 
two  gases  are  practically  absorbed  or  eliminated  in  any  other 
way." 

Operation  by  Servants. — Care  should  be  exercised 

in  placing  a  range  in  the  hands  of  a  professional  cook. 
This  type  of  individual  is  frequently  a  difficult  person 
to  handle.  He  seldom  favors  anything  new.  He  is 
prone  to  form  intense  prejudices;  and  will  often  re- 
fuse to  make  an  intelligent  investigation  of  new  appa- 
ratus, especially  when  he  has  not  been  previously  con- 
sulted. He  is  always  a  very  powerful  factor  in  matters 
concerning  the  management  of  a  kitchen,  and  his  posi- 
tion should  not  be  overlooked. 

If  he  dislikes  equipment  placed  in  his  charge  he 
may  damage  it,  refuse  to  handle  it  properly,  or  cause 
the  operating  cost  to  run  up  excessively.  Disastrous 
results  are  certain  to  accrue  if  the  cook's  attitude  is 
unfavorable. 


ELECTRIC    COOKING  33 

Repeated  experience  has  proved  that  the  house- 
wife who  does  her  own  cooking  is  the  most  desirable 
user  of  an  electric  range.  She  will  be,  as  a  rule,  thor- 
oughly alive  to  its  advantages,  will  practice  the  many 
little  economies  that  are  possible,  and  will  generally 
become  a  "booster"  for  electric  cooking. 

Attention  to  Range  Users. — When  ranges  are  first 
installed  the  users  should  receive  very  careful  atten- 
tion.    It  must  be  remembered  that  the  manipulation 


General    Electric   No.   S-3    Range. 

of  an  electric  range  is  entirely  new  to  the  average 
housewife.  If  something  about  the  apparatus  is  out 
of  order;  if  the  best  results  are  not  secured  at  the 
start ;  or  if  some  of  the  many  little  economies  that  may 
be  practiced  are  overlooked  and  the  first  month's  bill 
proves  higher  than  has  been  anticipated,  an  erroneous 
mental  impression  may  be  formed  that  may  prove  dif- 
ficult to  correct.  If  troubles  are  not  rectified  or  ex- 
plained away,  they  will  become  magnified  as  time 
passes,  and  the  housewife  may  finally  become  seri- 
ously prejudiced.  Furthermore,  every  electric  range 
placed  is  naturally  watched  by  the  many  friends,  rel- 
atives and  neighbors  of  the  user.  In  as  much  as  it 
is  generally  conceded  that  the  best  advertising  medium 


34 


ELECTRIC    HEATING 


is  the  satisfied  customer,  it  is  well  worth  while  to  give 
the  user  early  and  painstaking  attention. 

Electric  Cooking  in  Schools. — The  encouragement 
of  electric  cooking  in  the  domestic  departments  of  ed- 
ucational institutions  will  foster  the  more  rapid  intro- 
duction of  electric  ranges  in  the  homes.  In  order  that 
correct  impressions  may  be  created  in  the  minds  of  the 
students,  it  is  highly  important  that  the  equipment  be 
intelligently  selected,  that  the  apparatus  be  properly 
installed,  and  that  the  service  be  the  best  attainable. 


Domestic   Science   Classroom,   Westminster   College, 
Salt  Lake  City. 


For  classroom  work,  small  rather  than  large  in- 
dividual disc  stoves  should  be  installed,  because  only 
a  small  amount  of  food  need  be  prepared  at  one  time. 
Double  boilers  and  frying  pans  should  be  provided 
with  each  stove,  and  these  utensils  should  be  of  a  size 
to  fit  and  of  a  kind  that  w^ill  operate  properly  with  the 
particular  type  of  disc  stove  that  is  installed.  Small 
individual  bake  ovens  are  comparatively  inexpensive, 
occupy  little  space,  produce  excellent  results,  and  may 
be  recommended  for  well-equipped  departments. 

In  some  school  where  domestic  science  is  taught 
complete  electric  cooking  equipments  have  been  pro- 
vided and  meals  prepared  and  served  cafeteria  style 
during  the  noon  hour  periods.     The  income  from  the 


ELECTRIC     COOKING  35 

iioininal  charge  made  for  these  meals  has  been  ade- 
quate, in  a  number  of  instances,  to  pay  the  operating^ 
cost  of  the  electric  kitchen,  as  well  as  of  the  entire 
department. 

Other  institutions  have  gone  further,  and  arranged 
for  the  use  of  electric  flat  irons,  water  heaters,  and 
other  labor-saving  devices.  At  least  one  complete  elec- 
tric range  should  be  made  the  part  of  any  modern 
domestic  science  room  equipment.  The  comparatively 
few  hours  during  which  classes  are  in  session  make 
the  operating  cost  of  electrically  operated  installations 
very  small.     Although  the  income  from  this  class  of 


McDonald  Apartments,  Boston,  Equipped  with  Hughes  Ranges. 

business  is  not  large,  the  load  is  of  an  oiT-peak  char- 
acter, and  the  results  are  far-reaching.  The  favorable 
impression  created  by  equipping  domestic  science  de- 
partments in  this  manner  cannot  but  have  a  beneficial 
efifect  upon  the  school  and  a  credit  to  the  individuals 
in  charge. 

Electric  Cooking  in  Apartment  Houses. 

Adaptability  of  Electric  Range. — The  electric 
range  seems  to  be  peculiarly  adapted  for  use  in  apart- 
ment houses.  The  character  of  construction  of  the 
buildings,  the  mode  of  living  of  the  tenants,  and  the 
many  recognized  advantages  of  the  electric  range  make 
it  much  superior  to  the  fuel  burning  stove.  A  resume 
of  the  most  essential  qualifications  of  this  type  of  appa- 
ratus and  the  better  conditions  that  may  be  brought 
about  where  it  is  installed  for  apartment  house  cooking 
service  should  not  be  out  of  place  in  these  pages. 


36 


ELECTRIC    HEATING 


Jensen  ApartmL  nts.  Gieat  Falls,  Mont. 
Simplex   Ranges.) 


(Equipped  with 


Economy  in  Space. — In  the  design  of  the  modern 
apartment  house  every  foot  of  space  is  valuable  and 
the  architect  must  plan  to  utilize  it  to  the  best  ad- 
vantage. His  efforts  in  this  direction  seem  to  ha\'e 
resulted  in  the  laying  out  of  very  small  kitchens  which 
are  often  stufTy  and  poorly  ventilated.  The  electric 
range  is  best  fitted  to  meet  these  recognized  conditions 
for  several  reasons :  It  is  compact  in  construction,  and 
as  the  exterior  never  becomes  hot  enough  to  burn  the 
woodwork  it  may  be  placed  against  the  wall  and  there- 
by take  up  less  space.  The  unbearable  heat  of  a  fuel 
range  in  a  small  kitchen  is  eliminated.  There  is  no 
combustion  in  the  electric  range  and  it  neither  throws 
off  poisonous  fumes  nor  takes  up  the  life-giving  oxygen 
from  the  air. 

Expense  Saved. — The  initial  outlay  required  for 
the  installation  of  chimneys  and  gas  plumbing  may  be 
entirely  eliminated.  When  the  building  is  once  occu- 
pied the  periodical  expenditures  incident  to  repainting, 
retinting  and  repapering,  may  be  cut  in  half.  The 
very  nature  of  the  electric  range,  which  creates  no 
products   of   combustion,   and   which    overcomes    the 


ELECTRIC    COOKING 


37 


smoke,  moisture  and  grease  nuisances  peculiar  to  the 
fuel  range,  makes  the  frequent  refinishing  of  interiors 
unnecessary. 

Elimination  of  Hazard. — Where  fuel  stoves  are 
used  there  is  constant  danger  of  fire.  Gas  offers  the 
menace  of  asphyxiation  and  explosion.  The  careless 
opening  of  a  valve,  a  temporary  cut-off  of  the  main 
supply,  or  a  little  mistake  of  the  cook  or  housewife  may 


.|n::i::::H:|:;:||i;i:.j:.d.H|^::|n:j!H:iH::|^^^ 


Typical  Apartment  House  Cooking-  Load  Curve,  24  Ranges, 
75   kw.    Connected,    Maximum   Demand   11%    kw. 


result  disastrously.  In  as  much  as  the  electric  range 
produces  no  flame,  and  neither  utilizes  nor  gives  off 
any  explosive  or  poisonous  gas,  its  use  does  away  with 
all  danger  of  loss  of  life  or  property. 

Convenient  for  the  Tenant. — On  account  of  the  ab- 
sence of  soot  and  burned  foods,  the  utensils  used  on 
an  electric  range  are  easier  to  cleanse  both  inside  and 
outside.  Silverware  in  an  apartment  house  never  tar- 
nishes as  it  does  where  gas  is  used.  Unlike  gas,  elec- 
tricity throws  off  no  sulphur  fumes. 

Another  condition  that  goes  to  make  the  electric 
range  popular,  is  that  an  auxiliary  supply  of  hot  water 
is  usually  available  for  use  in  the  apartment  house, 
and  may  be  utilized  for  cooking  operations  to  attain 
quick  results. 


38  ELECTRIC    HEATING 

Desirable  Central  Station  Load. —  I^>om  an  oper- 
ating standpoint  the  apartment  house  business  is  very 
desirable  for  the  central  station  company.  The  load 
is,  for  the  most  part,  of  an  off-peak  character.  The 
load  factor  and  diversity  factor  are  both  unusually  at- 
tractive. The  maximum  demand  is  frequently  shown 
to  be  not  over  one-sixth  of  the  connected  load.  Com- 
pared with  apartment  house  lighting  and  elevator  loads 
the  business  is  obviously  more  desirable. 

Preparation  of  Food. 

Knowledge  of  Cooking  Valuable. — For  those  inter- 
ested in  the  sale  of  electric  ranges  or  in  the  building 
up  of  electric  cooking  loads,  a  general  understanding 
of  how  foods  are  prepared,  why  it  is  necessary  to  cook 
them,  and  the  best  methods' to  employ,  will  be  of  value. 
If  one  endeavors  to  interest  a  housewife  in  an  elec- 
tric range,  he  should  know  something  about  the  use 
to  which  it  is  to  be  applied,  otherwise  he  will  not  read- 
ily gain  her  confidence.  Anyone  familiar  with  the  fol- 
lowing paragraphs  as  well  as  with  the  natural  advan- 
tages of  electric  heat,  will  be  able  to  show  the  average 
housewife  wherein  electricity  is  superior  to  fuel  heat 
in  performing  the  various  cooking  operations  sug- 
gested. 

Reason  for  Cooking. — The  cooking  of  food  has 
much  to  do  with  its  nutritive  value.  Many  articles 
which  are  quite  unfit  for  nourishment  when  raw  are 
nutritious  when  cooked.  It  is  also  a  matter  of  com- 
mon experience  that  a  well  cooked  food  is  wholesome 
and  appetizing,  whereas  the  same  material  badly 
cooked  may  be  both  unhealthful  and  unpalatable. 

Purposes  gf  Cooking. — There  are  three  chief  pur- 
poses of  cooking.  The  first  is  to  change  the  mechan- 
ical condition  so  that  the  digestive  juices  can  act  upon 
the  food  more  freely.  The  second  is  to  make  it  more 
appetizing  by  improving  the  appearance  or  flavor,  or 
both.  Food  which  is  attractive  to  the  taste  quickens 
the  flow  of  saliva  and  other  digestive  juices,  and  thus 
aids  digestion.  The  third  is  to  kill  any  disease  germs, 
parasites,  or  other  dangerous  organisms  it  may  con- 


ELECTRIC    COOKING  39 

tain.     This  is  often  an  important  object,  and  applies 
to  both  animal  and  vegetable  foods. 

Cooking  of  Meats. — For  the  most  part  meat  is 
either  boiled,  stewed,  fried,  broiled  or  roasted.  In 
general,  it  is  probably  true  that  cooking  diminishes  the 
ease  of  digestion  of  most  meats.  It  may  also  remove 
considerable  quantities  of  the  nutrients. 

Boiling  of  Meat. — If  it  is  desired  to  heat  the  meat 
enough  to  kill  bacteria  in  the  inner  portions  of  the 
cut,  the  piece  must  be  exposed  to  the  action  of  heat 
for  a  long  time.  If  it  is  brought  slowly  to  a  boil,  a 
good  broth  will  be  obtained,  but  the  meat  will  be  tough 
and  tasteless. 

If  a  piece  of  meat  is  plunged  into  boiling  water  or 
very  hot  fat,  the  albumen  on  the  entire  surface  of  the 
meat  is  quickly  coagulated  and  the  crust  thus  formed 
resists  the  dissolving  action  of  water  and  prevents  the 
escape  of  the  juices  and  flavoring  matters.  Thus 
cooked,  the  meat  will  possess  the  desired  meaty  taste 
but  the  resulting  broth  will  not  be  considered  good. 

It  is  impossible  to  make  a  rich  broth  and  have  a 
juicy  highly  flavored  piece  of  meat  at  the  same  time. 
If  the  meat  alone  is  to  be  used,  it  should  be  plunged 
into  boiling  water  and  kept  at  that  temperature  for 
about  ten  minutes,  after  which  the  cooking  should  be 
continued  at  about  180  degrees  F.  until  the  tissues 
become  tender. 

Stewing  of  Meat. — If  both  the  broth  and  the  meat 
are  to  be  used,  the  process  of  cooking  should  be  quite 
dififerent  from  that  of  boiling.  In  stewing,  the  meat 
should  be  cut  into  small  pieces  so  as  to  present  rela- 
tively large  surface  area  and,  instead  of  being  quickly 
plunged  into  hot  water,  should  be  put  into  cold  water, 
in  order  that  the  juices  and  flavoring  materials  may  be 
dissolved.  The  temperature  should  then  be  slowly 
raised  until  it  reaches  about  180  degrees  F.  where  it 
should  be  kept  for  several  hours.  Treated  in  this  way 
the  broth  will  be  rich,  and  the  meat  tender  and  juicy. 

Roasting  of  Meat. — The  principle  difiference  be- 
tween roasting  and  boiling,  is  in  the  medium  in  which 
the  meat  is  cooked.    In  boiling  the  flesh  is  surrounded 


40  EL.ECTRIC    HEATING 

by  hot  water,  whereas  in  roasting  it  is  surrounded 
by  hot  air  and  acted  upon  to  some  extent  by  radiant 
heat.  In  both  operations,  if  properly  conducted,  the 
meat  fibers  are  cooked  in  their  own  juices. 

When  the  meat  only  is  to  be  eaten,  either  roast- 
ing, broiling,  or  frying  in  deep  fat  is  a  more  rational 
method  than  boiling,  for  the  juices  are  largely  con- 
served in  the  meat. 

Cooking  of  Vegetables. — Vegetables  baked,  roasted, 
fried  or  boiled,  are  used  for  preparing  a  large  variety  of 
dishes.  The  most  common  method  of  cooking  is  that 
of  boiling  in  water.  The  steaming  of  vegetables  is 
often  resorted  to,  but  the  results  are  similar  to  those 
of  the  boiling  process. 

The  simpler  the  method  of  cooking  and  serving 
vegetables  the  better.  A  properly  cooked  vegetable 
will  be  palatable  and  readily  digestible.  Poorly  cooked, 
water  soaked  vegetables  generally  cause  serious 
digestive  disturbances.  All  vegetables  should  be  thor- 
oughly cooked,  but  the  cooking  should  stop  while  the 
vegetable  is  yet  firm.  As  long  as  the  vegetable  is  kept 
at  a  temperature  above  125  degrees  F.  changes  con- 
tinue to  go  on  in  the  vegetable  substance.  The  most 
marked  of  these  are  in  the  starch,  and  in  the  odor, 
color,  and  flavor  of  the  vegetable.  Overcooking 
changes  and  toughens  the  texture  of  vegetable  foods, 
destroys  the  coloring  matters,  and  volatilizes  or  other- 
wise injures  the  substances  which  contribute  to  its 
flavor. 

Cooking  of  Breads  and  Pastries. — In  breads,  cakes, 
pastries  and  other  foods  prepared  from  flour,  the  aim 
is  to  make  a  palatable  and  higher  porous  substance 
that  can  be  more  easily  digested  than  the  raw  ma- 
terials could  be.  Sometimes  this  is  accomplished  sim- 
ply by  means  of  water  and  heat.  The  heat  changes 
part  of  the  water  content  into  steam,  which,  in  try- 
ing to  escape,  forces  the  particles  of  dough  apart.  The 
protein  (gluten)  of  the  flour  stiffens  about  the  tiny 
bubbles  thus  formed  and  the  mass  remains  porous  even 
after  the  steam  has  escaped.  More  often,  however, 
other  ingredients,  such  as  yeast  and  baking  powder. 


ELECTRIC    COOKING  41 

are  used  to  "raise"  the  dough.  The  baking  powder 
gives  off  carbon  dioxide  gas,  and  the  yeast  causes  fer- 
mentation in  the  dough  and  produces  carbon  dioxide. 
This  gas  acts  the  same  as  steam,  only  much  more 
powerfully. 

Baking  of  Bread. — Bread  is  placed  in  the  oven  as  a 
heavy  uniform  mass,  and  comes  out  a  light  body  of 
increased  volume  with  a  crisp,  dark  exterior — the  crust 
• — and  a  firm,  spongy  interior — the  crumb.  The  crumb 
naturally  heats  more  slowly  than  the  crust.  The  moist- 
ure which  it  contains  prevents  its  temperature  from 
rising  much  above  the  boiling  point  of  water  (212 
degrees  F.)  When  first  put  into  the  oven  the  yeast 
begins  to  work  but  a  temperature  of  158  degrees  F. 
kills  it.  The  gas  in  the  dough,  how^ever,  continues  to 
expand,  and  forcing  its  way  outward,  enlarges  the  loaf 
and  gives  it  a  spongy  appearance.  Meanwhile  the 
crust  becomes  hard  and  dark  and  the  heat  changes 
its  starch  into  stiff  gum  and  sugar  and  dries  out  the 
moisture.  The  brown  color  is  due  to  chemical  changes 
known  as  ''caramelization." 

Baking  Temperatures. — The  heat  in  the  oven 
should  not  be  too  great,  or  the  outside  of  the  bread 
will  harden  too  quickly,  and  the  crust  will  be  thick 
and  hard  before  the  interior  is  done.  Furthermore,  the 
gas  expanding  in  the  crumb  will  be  unable  to  escape 
through  the  crust  and  will  lift  up  the  latter,  leaving 
great  holes  beneath  it. 

The  temperature  of  an  oven  and  the  time  required 
for  baking  depends  upon  the  size  of  the  loaves  and 
the  character  of  the  dough.  Small  biscuits  or  rolls  can 
stand  a  much  hotter  oven,  and  quicker  baking,  than 
large  bread  loaves.  For  ordinary  purposes,  a  temper- 
ature of  from  400  degrees  to  500  degrees  F.  is  satis- 
factory for  a  pound  loaf  of  bread.  An  experienced 
cook  can  tell  when  an  oven  has  reached  the  proper 
heat  by  inserting  his  hand,  but  a  pyrometer,  (as  a 
thermometer  for  measuring  high  temperature  is  called) 
makes  a  much  better  guide  for  the  ordinary  operator. 


CHAPTER  V 

THE  ELECTRIC  RANGE. 

Demand  for  Domestic  Ranges. — Interest  shown  in 
the  domestic  range  is  increasing  more  rapidly  than  in 
any  other  single  heating  appliance.  In  line  with  the 
attention  now  being  given  to  this  type  of  apparatus, 
and  the  rapidly  growing  market  for  it,  the  manufac- 
turers of  heating  apparatus  are  making  many  improve- 
ments in  both  their  original  designs,  and  character  of 
product.  A  number  of  concerns  which  have  heretofore 
confined  their  activity  solely  to  the  production  of  fuel 
stoves,  have  taken  up  the  manufacture  of  electric 
ranges.  The  result  of  these  developments  has  been  a 
50  per  cent  reduction  in  range  prices  during  the  past 
five  years,  greater  reliability  in  the  heating  units,  a 
larger  diversity  of  designs  from  which  choice  of  equip- 
ment can  be  made,  and  simpler  and  more  desirable 
standards  of  construction. 

Essential  Qualifications  of  the  Electric  Range. — 
The  features  of  the  domestic  range  which  make  its  use 
desirable  to  the  customer,  the  central  station,  and  to 
those  having  the  marketing  of  the  product  in  hand,  are 
generally  agreed  upon  by  all  who  have  given  the  sub- 
ject their  serious  consideration.  The  range,  first  of  all, 
must  be  of  substantial  and  durable  construction,  and 
of  pleasing  appearance.  The  designs  must  be  stand- 
ardized as  rapidly  as  possible  with  the  economic  object 
in  view  of  lower  costs  and  increasing  production.  Sim- 
plicity of  operation  and  ease  of  handling  and  clean- 
ing are  also  essential.  The  heating  elements  must  be 
rugged,  reliable  and  efficient.  Furthermore,  they 
should  be  so  designed  as  to  be  easily,  quickly,  and 
cheaply  renewed  whenever  troubles  develop.  The 
ovens  must  be  well  insulated  with  heat  resisting  ma- 
terial, readily  accessible,  and  easily  cleaned.  Some 
provision  for  broiling,  either  in  the  oven  or  on  the 
cooking  surface,  is  generally  considered  necessary. 


THE    ELECTRIC    RANGE  43 

It  is  of  interest  to  note  that  the  early  types  of 
ranii^es  were  so  designed  as  to  keep  down  the  connected 
load  and  the  central  station  demand  as  much  as  pos- 
sible, whereas  the  present  tendency  is  to  neglect  this 
phase  of  the  design  in  favor  of  larger  capacity  units 
capable  of  doing  quicker  work.  This  is  a  step  in  the 
right  direction.  The  natural  diversity  of  the  range 
load,  and  the  short  period  demands  which  it  creates  are 
of  little  moment  in  comparison  with  the  necessity  for 
greater  speed  of  operation.  Furthermore,  there  is  no 
reason  for  believing  that  a  range  of  high  rated  capacity 
will  consume  any  more  energy  in  performing  its  work 
than  one  of  lower  capacity.  The  efficiency  may  be 
approximately  the  same  with  either  design. 

Types  of  Heating  Units. — Heat  is  usually  gener- 
ated in  electric  range  units  by  the  passage  of  current 
through  high  resistance  wires  or  strips  of  metallic 
ribbon.  Heating  elements  in  common  use  may  be 
classified  into  three  diflferent  types — first,  the  enclosed 
type,  second,  the  radiant  type,  and  third,  the  reflector 
type. 

Enclosed  Type  Elements. — These  usually  consist 
of  a  resistance  wire  or  ribbon,  enclosed  between  mica 
or  asbestos  strips,  or  surronded  with  an  enamel  or  other 
electric  insulating  material  of  high  thermal  conduc- 
tivity. The  element  is  usually  enclosed  within,  bound 
upon,  or  otherwise  imposed  against,  a  metal  disc  or 
grid  which  takes  up  the  heat,  and  in  turn  dissipates 
it.  The  heat  generated  in  such  a  unit  is  transmitted 
from  the  metal  surface  to  the  cooking  utensil  and 
thence  to  the  food  by  conduction.  When  this  type  of 
unit  is  used  in  an  oven,  however,  the  heat  is  trans- 
mitted to  the  food  through  the  air  by  convection. 

It  is  obvious  that  this  type  of  element  takes  a 
little  longer  to  start  heating  than  do  open  elements, 
because  the  mass  of  material  of  which  it  is  composed 
has  to  first  absorb  a  certain  quantity  of  heat  before  it 
can  begin  throwing  it  oflf.  It  is  claimed,  however, 
that  this  type  of  element  will  lose  less  of  the  heat 
generated  during  a  longer  period  of  operation  than  the 
open  coil  element.    There  are  certain  apparent  advan- 


44 


ELECTRIC    HEATING 


tages  in  having  the  hot  wires  hermetically  sealed,  such 
as  the  prevention  of  oxidation  and  mechanical  injury, 
but  unless  the  insulating  materials  are  able  to  withstand 
extreme  temperatures  they  are  liable  to  serious  dam- 
age, if  the  voltage  is  higher  than  normal,  or  if  the  ele- 
ment is  connected  for  a  long  period  without  some 
means  of  carrying  away  the  excess  heat  that  is  gener- 
ated. Most  enamels  melt  before  they  reach  a  tem- 
perature of  1650  degrees  F.  (Cherry  red). 


SCCTION  fl-A 

CNLARCLD 


SECTION  B-B 


Process  of  Manufacture  of  General  Electric  Sheath  Wire  Heat- 
ing Elements. 

Radiant  Type  Units. — These  are  usually  coils  of 
high  resistance  wire  laid  in  grooves,  or  supported  on  the 
surface  of  insulating  material.  Current  passing  through 
this  wire  brings  it  to  a  high  temperature,  and  the  heat 
is  transmitted  for  the  most  part  as  radiant  heat  direct 
to  the  utensil  or  the  food  to  be  cooked.  Some  of  the 
heat,  however,  is  absorbed  by  the  insulating  support 
and  some  is  given  off  as  convected  heat  both  from 
the  support  and  from  the  wire  itself,  the  percentage 
varying  with  the  design  of  the  unit  and  its  composition. 
In  a  well  designed  unit  much  of  this  convected  heat 
is  finally  taken  up  by  the  food. 

Radiant  type  units  begin  to  throw  off  a  large 
amount  of  heat  almost  as  soon  as  the  current  is  turned 
on.  The  heat  in  the  coils,  is  visible  on  account  of 
the  high  temperature.    The  nature  of  the  radiant  heat 


THE    ELECTRIC    RANGE  45 

given  off  makes  it  possible  to  use  the  ordinary  kitchen 
utensils  to  better  advantage  on  the  open  than  on  the 
enclosed  type  elements.  The  coils  being  exposed, 
however,  and  the  supports,  as  now  manufactured,  being 
somewhat  brittle,  this  type  of  unit  is  to  some  extent 
liable  to  mechanical  injury,  short  circuits,  and  grounds. 
It  is  also  harder  to  keep  clean  than  the  enclosed  type 
element. 


Hug-hes   Open-Type   Element. 

Reflector  Type  Element. — Use  is  here  made  of  the 
heat  reflection  principle.  It  usually  consists  of  exposed 
coils  of  wire  surrounded  by  air  and  supported  adjacent 
to  a  bright  metallic  reflector.  Part  of  the  heat  generated 
in  the  coils  passes  directly  to  the  cooking  utensil  or 
to  the  food  in  the  same  manner  as  from  the  ordinary 
radiant  type  element.  Another  portion  of  the  heat 
travels  in  the  opposite  direction  until  it  reaches  the 
polished  surface,  where  it  is  reflected  back  on  its  course 
to  the  cooking  utensil.  A  small  percentage  of  the  en- 
ergy is,  of  course,  given  oflf  as  convected  heat  and  some 
passes  away  through  the  reflector. 

This  type  of  element  heats  quickly,  makes  possi- 
ble the  use  of  most  ordinary  kitchen  utensils,  and  pro- 


46  ELECTRIC    HEATING 

duces  a  visible  heat  in  the  coils.  It  is,  however,  more 
subject  to  mechanical  injury  than  the  enclosed  type 
element.  The  reflectors,  although  they  can  be  easily 
and  cheaply  replaced,  are  also  likely  to  become  discol- 
ored and  become  inefficient  on  account  of  the  intense 
heat.  The  future  development  of  a  cool  reflector,  how- 
ever, may  do  away  with  the  latter  objection. 

Types  of  Electric  Ranges. 

A  large  variety  of  electric  ranges  are  manufac- 
tured in  this  country.  They  are  available  in  many 
styles  and  capacities,  and  at  various  prices.  Each  of 
them  has  been  developed  with  certain  individual 
characteristics  in  design  or  operating  features,  having 
some  advantages  over  those  of  other  makes,  but  all 
of  which  could  not  possibly  be  incorporated  in  any 
single  design.  This  chapter  is  therefore  devoted  to 
descriptions  of  the  most  prominent  makes  of  electric 
ranges  in  order  to  convey  a  general  understanding  of 
the  design,  construction  and  individual  characteristics 
of  the  types  now  available. 

Hughes  Ranges. — This  make  of  electric  range  has 
been  on  the  market  for  a  number  of  years.  It  is  made  in 
a  large  variety  of  shapes  and  sizes,  in  either  the  high 
oven,  low  oven,  or  cabinet  types,  and  in  capacities 
ranging  from  4140  to  10,340  watts.  The  frame  is  con- 
structed of  black  heavy  gauge  sheet  metal  supported 
on  cast  iron  legs.  The  legs,  top,  and  fittings  are  nickel 
finished  in  most  of  the  designs.  The  general  con- 
struction is  rugged  and  of  handsome  appearance. 

The  heating  elements  are  of  the  open  or  radiant 
type  and  consist  of  coils  of  resistance  wire  held  in 
place  below  the  cooking  surface  by  means  of  a  grooved 
composition  block.  This  block  is  in  turn,  surrounded 
by  another  block  of  asbestos  compound  having  high 
thermal  resistance.  The  units  may  be  easily  removed 
with  a  screw  driver  and  pliers. 

The  oven  is  thoroughly  insulated  with  mineral 
wool.  The  interior  of  the  oven  is  finished  in  black 
enamel.  The  doors  are  of  the  drop  shelf  type  and  are 
usually  trimmed  in  nickel  and  white  porcelain  enamel 


THE    ELECTRIC    RANGE 


47 


Thermometers  are  fitted  in  these  doors.  There  are  two 
heating  elements  in  the  oven — one  in  the  top,  and 
the  other  in  the  bottom.  Each  of  these  units  is  regu- 
lated by  a  three  heat  switch.  The  top  unit  is  used 
for  broiling.  An  enameled  tray  and  rack  for  this  pur- 
pose are  provided  with  each  range.  Some  of  the 
higher  priced  ranges  are  supplied  with  white  porce- 
lain enamel  splashers  around  the  cooking  surfaces, 
which  add  materially  to  the  appearance  of  the  equip- 
ments. 


Type. 
No.  Style. 


C-2 
C-3 

C-4 


Cabinet 
Cabinet 

Cabinet 


Wattage. 

2-880 


HUGHES  RANGES. 

Cook 

Oven No. 

Dimensions.      Elemen 

18x12x12 


2-880 


18x12x12 


2-1100        18x18x12 


C-18  Low  oven 
No.  27  Low  oven 
No.  30   Low   oven 


2-880 
2-880 
2-880 


18x12x12 
18x12x12 
18x12x12 


No.  33   High   oven  2-880  18x12x12 

No.  37   Low   oven  2-1100  18x18x12 

No.  40   Low  oven  2-1100  18x18x12 

No.  44   High   oven  2-1100  18x18x12 


No.  47   Cabinet 


2-1100        18x18x12 


W^armer-      21i4x20x9 
No.  48   Low   oven       2-1100        18x18x12 


No.  50   Cabinet  2-1100        18x18x12 

W^armer-      211^x20x9 


No.  56   Cabinet 
No.  60   Cabinet 


1-1800  18x18x8 

2-1100  18x18x12 

Warmer-  21^/4x20x9 

1-1800  18x18x8 

2-1100  18x18x12 

Warmer-  21^/4x20x9 


ng  Surface.     Total 

Wattage  Wattage 
s.  (of  Each)  of  Range. 


1500 

880 

1500 
1100 

880 

1500 
1100 

880 

1500 

880 

1500 

880 

1500 
1100 

880 

1500 
1100 

880 

1500 
1100 

880 

1500 
1100 

880 

1500 

1100 

880 

1500 

1100 

880 

1500 
1100 

880 

1500 

1100 

880 

1500 

1100 

880 

1500 

1100 

880 


4140 

5240 

5680 
4140 
4140 

5240 

5240 

5680 

6560 

6560 

5680 

8540 

6560 

8360 

10340 


48 


ELECTRIC    HEATING 


Hughes  No.  50  Cabinet  Range. 


Simplex  Ranges. — These  ranges  were  first  put  on 
the  market  about  nineteen  years  ago.  The  modern 
domestic  types  usually  consist  of  an  oven,  a  broiler, 
and  several  disc  heaters.  They  are  made  up  in  either 
the  low  oven,  or  cabinet  type,  and  in  capacities  rang- 
ing from  3100  to  8200  watts.  They  are  finished  in 
black  japan.  The  general  construction  is  rugged  and 
compact. 

The  heating  units  are  of  the  enclosed  type,  the 
resistance  wires  being  embedded  in  enamel,  and  fused 
to  the  under  side  of  the  cast  iron  discs.  The  discs 
protrude  slightly  above  the  top  of  the  range,  and 
are  provided  with  a  simple  locking  device  by  which 
the  utensils  are  clamped  fast  to  the  heating  surface 
to  insure  good  contact.  The  units  are  fastened  to  the 
frame    with    thumb    screws.     The    utensils    included 


THE    ELECTRIC    RANGE 


49 


with  each  range  are  made  of  heavy  copper,  nickeled 
outside  and  tinned  inside. 

The  broiler  is  mounted  on  the  cooking  surface. 
It  consists  of  a  corrugated  heating  plate  slightly 
inclined  toward  the  front,  from  which  an  outlet  carries 
off  the  juices  for  serving  with  the  meat.  A  separate 
smooth  top  fits  on  the  broiler  for  making  griddle 
cakes,  etc. 

The  oven  is  made  of  Russia  iron  with  japan  finished 
iron  frame  and  nickel  plated  trimmings.  The  walls 
are  heavily  insulated  with  corrugated  asbestos  and 
provided  with  a  vent.     The  heating  elements  in  both 

SIMPIiEX  RANGES. 

Cooking  Surface.  Total 


Type. 
No.             Style. 

Wattage. 

—Oven No.  of 

Dimensions.      Elements. 

Wattase 
(of  Each) 

Wattage 
of  Range, 

4K 

Low  oven 

1300 

15x12x111/2 

1 
2 

440 
735 

3210 

5K 

Low  oven 

1300 
1300 

15x12x111/2 
9x12   broiler 

1 
1 

440 
735 

3775 

6K 

Low   oven 

1600 
1300 

15x18x111/2 
9x12   broiler 

2 

J. 

440 
735 

4515 

7K 

Low   oven 

1600 
1300 

15x18x111^ 
9x12   broiler 

1 
2 

440 
730 

4810 

8K 

Low  oven 

1600 
1300 

15x18x111/2 
9x12   broiler 

2 
2 

440 
735 

5250 

9K 

Low   oven 

1600 
1300 

15x18x111/2 
9x12   broiler 

1 
2 

i 

440 

735 

1100 

5910 

14K 

Low  oven 

2400 
2200 

211/2x19x13 
12x18   broiler 

1 
1 

1 
1 

440 

735 

1100 

1300 

8175 

21K 

Cabinet 

1600 

1300 

200 

15x18x111/2             2 
9x12  broiler         1 
15x15x7   warmer 

440 
735 

4715 

22K 

Cabinet 

1600 

1300 

200 

15x18x111/2 
9x12   broiler 
15x15x7   warmei 

1 

2 

440 
735 

5010 

23K 

Cabinet 

1600 

1300 

200 

15x18x111/2             2 
9x12   broiler         2 
15x15x7   warmer 

440 
735 

5450 

24K 

Cabinpt 

1600 
1300 
200 

15x18x111/2 
9x12   broiler 
15x15x7   warmer 

1 
2 
1 

440 

735 

1100 

6110 

31K 

Cabinet 

1600 
1300 

15x18x111/2 
9x12   broiler 

2 
1 

440 
735 

4515 

32K 

Cabinet 

1600 
1300 

15x18x111/^ 
9x12   broiler 

1 
2 

440 
735 

4810 

33K 

Cabinet 

1600 
1300 

15xl8xllV2 
9x12   broiler 

2 
2 

440 
735 

5250 

34K 

Cabinet 

1600 
1300 

15x18x111^ 
9x12  broiler 

1 
2 
1 

440 

735 

1100 

5910 

50 


ELECTRIC    HEATING 


Simplex  No.    7-K   Range. 


top  and  bottom  are  of  the  enclosed  grid  type,  and 
are  controlled  by  a  single  three-heat  switch.  The  oven 
door  is  of  the  drop  shelf  type,  fitted  with  an  indicating 
thermometer. 

General  Electric  Ranges. — Ranges  of  this  make 
have  been  on  the  market  for  a  considerable  time  and 
the  makers  may  be  credited  with  having  done  a  great 
deal  of  development  work.  These  ranges  are  now 
manufactured  in  two  standard  types — the  "R"  type 
and  the  "S"  type,  either  of  which  are  available  in  either 
the  high  oven,  low  oven,  or  cabinet  styles. 

The  **R"  type  was  first  developed.  It  is  of  heavier 
and  better  construction,  provided  with  special 
"Calorox"  oven  insulation,  and  is  likewise  more  ex- 
pensive. 

The  ''S"  type  is  a  later  development.  The  frame 
of  the  range  is  made  by  a  fuel  stove  manufacturing 
concern.  The  heating  units  and  other  electrical  fea- 
tures are  provided  by  the  General  Electric  Company. 


THE    ELECTRIC    RANGE 


51 


General  Electric  No.  R-2  Range 


The  ovens  are  equipped  with  separate  top  and 
bottom  heating  elements  and  provision  made  for 
broiling  inside.  The  standard  oven  dimensions  on  each 
range  is  18  in.  by  18  in.  by  12  in. 

It  is  of  interest  to  note  that  all  the  heating  ele- 
ments used  on  ranges  made  by  this  company  have  been 
of  the  enclosed  type.  The  ''D"  type  unit  which  has 
been  discarded  for  some  time,  consisted  of  a  ribbon 
wire  resistance  clamped  between  mica  strips  and  fas- 
tened to  the  bottom  of  the  element.  The  units  used 
on  the  "R"  and  "S"  type  units  are  made  up  by  pour- 
ing molten  iron  around  sheathed  wire.  This  so  called 
"sheated  wire"  consists  of  a  small  hollow  wire  enclos- 
ing a  fine  resistance  wire,  the  space  between  being 
filled  with  an  insulating  material  of  high  thermal  con- 


52 


ELECTRIC    HEATING 


GENERAL  ELECTRIC  RANGES. 


Type. 

Style. 

( 

3ven 

Dimensions. 

Cooking 
No.  of 
Elements. 

Surface. 
Wattage 
(of  Each) 

Total 
Wattage 
of  Range. 

No. 

Wattage. 

R-1 

Low  oven 

2-1000 

18x18x12 

2 
3 

1000 
200* 

4600 

R-2 

High  oven 

2-1000 

18x18x12 

2 

3 

1000 
200* 

4600 

R-3 
R-4 

Cabinet  oven 
Cabinet  oven 

2-1000     18x18x12 
1-300   warmer 
2-1000      18x18x12 

2 
3 
2 

3 

1000 
200* 

1000 
200* 

4900 
4600 

S-1 

Low  oven 

1-1000 
1-1500 

18x18x12 

3 

1000 

5500 

S-2 

High  oven 

1-1000 
1-1500 

18x18x12 

3 

1000 

5500 

S'-3 

Cabinet  oven 
(♦cookers) 

1-1000 
1-1500 

18x18x12 

3 

1 

1000 
200* 

5700 

due 

tivity    (presi 

amably 

aluminum    or    other    metallic 

oxide). 

Vegetable  cookers  may  be  substituted  for  any  one 
or  all  of  the  top  heating  units  if  desired.  These  cook- 
ers are  heavily  insulated  and  consume  little  current. 
They  are  especially  useful  for  preparing  stews,  vege- 
tables, cereals,  etc. 

All  the  elements  on  the  stove  have  plug  connec- 
tions and  may  be  changed  by  anyone  without  the  use 
of  any  tools. 

Westinghouse  Ranges  (Copeman  Patents). — These 
ranges  are  at  present  manufactured  in  two  standard 
styles — the  low  oven  type  known  as  the  2-19,  and  the 
cabinet  type  known  as  the  3-19.  Either  of  these 
ranges  may  be  obtained  in  either  plain  or  nickel  finish, 
and  may  or  may  not  be  provided  with  the  special 
automatic  feature.  The  cabinet  type  is  always 
equipped  with  white  porcelain  enamel  splashers  around 
the  cooking  surface.  The  construction  of  both  ranges 
is  substantial.  The  legs  and  frame  are  of  cast  iron, 
and  other  parts  of  sheet  steel. 

Open  or  radiant  type  elements  consisting  of  coils 
of  resistance  wire,  held  in  place  in  spiral  grooved  com- 
position blocks  are  used.  The  cooking  surface  on 
each  of  these  ranges  consists  of  two  8  in.  1000  watt 
units,  and  one  10  in.  2000  watt  unit.  The  latter  is  so 
connected  that  the  low  heat  utilizes  the  inner  third 


THE    ELECTRIC    RANGE 


53 


» 


I 


I 


Westinghouse  3-19  Automatic  Range. 

of  the  surface,  medium  the  inner  two-thirds  of  the 
surface,  and  high  the  entire  10  in.  surface. 

The  ovens  are  thoroughly  insulated  with  mineral 
wool.  The  oven  doors  open  to  the  side.  The  interior 
dimensions  of  the  oven  are  18>^  by  13^  by  16  in.  The 
cabinet  type  range  is  provided  with  a  small  boiling 
oven  (10^  in.  by  ISjA  in.  by  11>^  in.)  in  addition  to 
the  large  oven.  Provision  is  made  also  for  broiling 
in  the  large  oven. 

Either  type  range  may  be  equipped  with  a  relay, 
whereby  the  current  will  be  automatically  turned  off 


54  ELECTRIC    HEATING 

WESTIXGHOUSE   RAIVGKS. 

Cooking   Surface.  Total 

Type.  0\en -\o.  of        Wattage.     Wattage 

No.  Style.  Wattage.      Dimensions.  Elements. (of  Each)  of  Range. 

No.  3-19   Cabinet        2-1000   181/2x131/2x16  1  2000 

1-850      10  %xl3 1/2x11 1/2  2  1000  6850 

No.  2-19   Low  oven    2-1000   18  1/2x13  1/2 xl 6  1  2000 

2  loOO  6000 

No.  406      Low  oven    1-1000    16x12x111/2  2  1000 

1-660  3660 

when  the  ovens  reach  a  certain  desired  temperature. 
The  cabinet  type  range,  furthermore,  may  be  equipped 
with  a  clock  device,  whereby  the  current  may  be  auto- 
matically turned  on  in  the  oven  at  any  desired  time. 

The  number  406  range  is  smaller  than  the  two 
standard  styles  and  of  less  expensive  construction. 

Olston  Ranges. — These  ranges  have  been  on  the 
market  for  several  years  and  are  made  in  one-oven, 
two-oven,  and  three-oven  types  and  in  capacities  vary- 
ing from  1980  watts  to  4620  watts.  They  are  con- 
structed of  sheet  iron,  enameled  in  gray,  and  trimmed 
in  nickel.  The  ovens  are  mounted  on  sheet  metal 
legs,  and  are  easily  accessible  without  stooping. 

No  heating  elements  are  furnished  for  top  cook- 
ing, but  flush  receptacles  for  attaching  disc  stoves  and 
other  heating  devices,  are  provided.  The  oven  ele- 
ments are  of  the  open  type. 

OLSTEN   RANGES. 

Total 

Type.  Oven \\attage 

No.  Style.  Wattage.  Diniens  ons  of  Range. 

1  Low  1980  111/2x111^x18  1980 

2  Low  2970  (111^x111^x18 

(iiy2Xllv2Xl8  2970 

3  Low  4620  (lli/2xliy2Xl8 

X  i  i      >  X 


4  Wall  type.     Same  as  No.   1. 

5  Wall  type.     Same  as  No.  2. 


(13  %xl2 1/2x21)  4620 


The  ovens  are  heavily  insulated  with  mineral  wool 
and  are  provided  with  drain  cups  to  collect  the  excess 
moisture  caused  by  condensation.  The  doors  open  to 
the  side.  The  ovens  are  controlled  by  flush  snap 
switches  and  the  temperatures  are  regulated  by  ther- 
mostatic devices,  which  automatically  maintain  any 
desired  temperatures  for  which   they  are  set.     When 


THE    ELECTRIC    RANGE 


55 


the  required  heat  is  generated,  the  current  switches 
off,  and  v/hen  the  oven  cools  a  few  degrees,  the  cur- 
rent is  switched  on,  thus  maintaining  a  constant  tem- 
perature. Pilot  lamps,  mounted  over  the  temperature 
control  dials,  indicate  at  all  times  whether  or  not 
current  is  being  consumed. 


No.   C   Good    H( 


■keeping  Cooker, 


Good  Housekeeping  Cocker. — This  device,  which 
has  been  on  the  market  for  several  years,  has  been 
known  as  the  automatic  steam  cooker,  or  the  Berkeley 
cooker.  Although  the  principle  of  operation  has  not 
been  changed,  its  mechanical  construction  has  been 
greatly  improved. 

The  cylindrical  outside  shell  is  14  inches  in  diam- 
eter and  made  of  polished  sheet  steel.  The  cast  iron 
base  and  top  are  trimmed  in  nickel.  Two  8  inch 
enclosed  type  disc  elements  of  1000  watts  capacity  each, 
may  or  may  not  be  -mounted  on  the  cooker  surface. 
The  top  of  the  cooker  is  31^^   in.  from  the  floor.     A 


56  ELECTRIC    HEATING 

GOOD    HOUSBKGKPING   COOKER. 

Cooking  Surface.  Total 

Type.                        Cooker  Pot No.  of          Wattage  Wattage 

No.             Style.              Wattage.       Dimensions.      Elements,     (of  Each)  of  Range. 

A              Cooker              550          14   gallons        None  550 

C            Cooker                550          14   gallons            2               1000  2550 

small  ovenette,  for  use  over  one  of  the  discs,  may  be 
obtained  with  the  cooker.  The  space  provided  in  the 
cooker  is  approximately  13  inches  deep  and  has  a 
capacity  of  about  14  gallons.  The  walls  and  cover 
are  heavily  insulated  with  mineral  wool  and  granulated 
roasted  cork. 

The  cooking  compartments  consist  of  two  cylin- 
drical copper  jackets  welded  one  within  the  other  with 
a  slight  space  between,  from  which  the  air  is  exhausted, 
and  a  small  quantity  of  water  and  ether  introduced. 
An  enclosed  type  heating  element  of  550  watts  capacity 
is  fastened  to  the  bottom  of  the  outer  jacket.  A  dia- 
phragm, the  buckling  of  which,  actuates  a  contact 
lever  controlling  the  flow  of  current  in  the  heating 
element,  is  made  a  part  of  the  outer  compartment 
jacket.  At  a  temperature  of  250°  F.,  a  steam  pressure 
of  15  pounds  is  produced  causing  the  diaphragm  to 
buckle,  thereby  actuating  the  lever,  and  cutting  off 
the  current  to  the  heating  element.  At  220°  F.  the 
pressure  is  reduced  with  the  result  that  the  element 
is  again  connected.  This  action  is  continued  as  long 
as  the  cooker  is  in  service.  An  automatic  clock  device, 
for  turning  the  current  on  in  the  cooker  at  a  prede- 
termined time,  is  also  provided  with  each  equipment. 

Globe  Ranges. — The  Globe  Stove  and  Range  Com- 
pany which  has  confined  its  efforts  to  the  production 
of  wood,  coal  and  gas  stoves,  for  many  years  has  re- 
cently taken  up  the  manufacture  of  electric  ranges. 
Those  w^hich  have  thus  far  been  placed  on  the  market 
possess  several  novel  and  attractive  features.  The 
desire  of  the  average  women  for  bright  enamel  and 
nickel  trimmings  has  been  catered  to  in  the  finish  of 
the  ranges.  The  sheet  metal  parts  are  made  of  twenty 
gauge  Armco  iron  with  white  enamel  on  one  side,  and 
ground  coat  on  the  other. 

The  ovens  are  insulated  with  three  inches  of 
"Sil-o-cel"  and  lined  with  sixteen  gauge  Armco  iron. 


THE    ELECTRIC    RANGE 


57 


One-quarter  inch  steam  packing  gaskets  insulate  the 
oven  from  the  front  frame  of  the  stove,  and  also  sep- 
arate the  inner  and  outer  casings  of  the  door.  Heavy- 
latches  used  on  the  oven  doors  make  them  practicall}' 
air  tight. 


Globe  No.   B-5  Range. 


The  heating  elements  used  in  the  oven  are  of  the 
enclosed  type  in  the  bottom,  and  of  the  open  coil 
radiant  type  in  the  top,  for  broiling  operations.  The 
top  surface  elements  are  unique  in  that  they  combine, 
in  a  measure,  the  features  of  both  the  open  and  en- 


58 


ELECTRIC    HEATING 


closed  types.  Resistance  wires,  wound  in  flat  helical 
coils,  are  fastened  in  grooved  porcelain  plates,  and 
protected    with    thin    cast    iron    plates      ^'  '   ' 

are  grooved  to   correspond 


These    plates 
with   the   position   of  the 


globe:  ranges. 


Tjpe. 

Style. 

c 

Oven                         N 

'ooking 
0.  of 
ments. 

Surface. 

Wattacre 
(of  Each) 

Total 

Wattaf?e 

of  Range. 

No. 

Wattage. 

Dimensions.      Ele 

A2 

Dow  oven 

1-1500) 
1-2000) 

191^x19^x13 

2 

1500 

Low  oven 

1-1500) 
1-1000) 

liy2Xl9%xl3 

2 

800 

10.600 

A3 

Cabinet 

1-1500 
1-1000 

Iiy2xl9%xl3 

9 
2 

1500 
800 

7.100 

A4 

Low  oven 

1-1500 
1-1000 

Il%xl9%xl3 

2 

2 

1500 
800 

7,100 

Bl 

Low  oven 

1-1500 
1-1000 

13^4x1314x1914 

2 
2 
1 

1500 
800 
330 

7.430 

B2 

Cabinet 

1-1500 
1-1000 

13%xl3i4xl9i4 

2 
2 

1 

1500 
800 
330 

7.430 

B3     Low  oven 
Special 

1-1500 
1-1000 

13  1/4x19 1/4  X131A 

2 

1 

1500 
800 

6,300 

B3 

Low  oven 

1-1500 
1-1000 

I3V4XI914XI31/4 

2 
1 

1500 
330 

5,830 

B4     Cabinet 
Special 

1-1500 
1-1000 

131/4x191/4x131/4 

2 

1 

1500 
800 

6,300 

B4 

Cabinet 

1-1500 
1-1000 

1314x1914x13^ 

2 

1 

1500 
330 

5,830 

B5 

High   oven 

1-1500 
1-1000 

131/2x191/2x131/2 

2 
1 
2 

1500 
330 
800 

7,430 

wires.  It  is  therefore  apparent  that  a  utensil  placed 
over  one  of  the  heatins:  elements  is  heated  by  both 
radiant  and  conducted  heat. 

Estate  Ranges. — The  Estate  Stove  Company  is  re- 
cently bringing  to  bear  its  many  years  of  experience 
in  the  construction  of  fuel  stoves  and  ranges,  in  the 
manufacture  of  electric  ranges.  Three  standard  tyr>^'^ 
have  thus  far  been  placed  on  the  market.  The  ranges 
are  of  substantial  construction,  resembling  the  stand- 
ard gas  ranges  in  appearance.  The  cast  iron  parts 
are  treated  with  a  coat  of  ebonite,  and  the  sheet  metal 
parts  are  made  of  rust  resisting  steel.  The  oven  doors 
and  broiler  pans  are  of  white  enamel,  as  are  the 
splasher  backs  in  the  cabinet  type  ranges. 

The  cooking  surface  elements  are  of  the  enclosed 
type,  consisting  of  nichrome  wire,  wound  around  mica 


THE    ELECTRIC    RANGE  59 

discs,  and  clamped  between  iron  plates.  These  plates 
are  connected  by  means  of  plugs  which  fit  into  re- 
ceptacles and  may  he  removed  or  connected  as  easily 
as  any  ordinary  socket  plug.  The  heating  elements 
in  the  ovens  are  also  of  the  iron  clad  type  with  the 


No.   S4   Estate  Range    (with  Cookers  Attached). 

exception  of  the  broiling  elements,  which  are  of  the 
radiant  type. 

The  ovens  are  of  ample  capacity  for  ordinary 
baking  and  roasting,  and  are  heavily  insulated.  The 
doors,  which  open  to  the  side,  are  strongly  latched 
and  fitted  with  thermometers.  Broiling  operations  are 
performed  in  the  ovens,  except  in  the  No.  84  cabinet 
range,  which  is  provided  with  a  separate  broiling  com- 
partment mounted  below  the  oven. 

The  cylindrical  fireless  cookers,  which  may  be 
hinged  to  the  legs  of  the  cabinet  type  ranges  and  swung 
out  of  the  way  when  not  in  use,  are  a  special  feature. 
These  cookers  are  heavily  insulated,  have  interior 
dimensions  of  8  inches  depth  by  10  inches  diameter, 
and  consume  500  watts  each.  . 


60 


ELECTRIC    HEATING 


ESTATE   RANGES. 


Tvi-f. 

Style 

Wattage. 

Cooking 
No.  of 
Elements. 

Surface.           Total 
Wattage     W.ittage 
(of  Each)  of  Range. 

No. 

Dimensions. 

83 

Low  oven 

1030) 
1370) 

18x12x12 

2-61/2  in. 
1-8       in. 

650 
1200 

4900 

84 

Cabinet 

1500) 
2000) 

1500 

18x18x12 
Broiler 

3 -6 1/2  in. 
1-8       in. 

650 
1200 

8150 

88 

Cabinet 

1500) 
2000) 

18x18x12 

3-6 1/2  in. 
1-8       in. 

650 
1200 

6650 

Rutenber  Ranges. — After  several  years  experience 
in  the  manufacture  of  electric  ranges  the  Rutenber 
Electric  Company  has  adopted  three  standard  low  oven 
types  which  are  made  up  in  either  plain  or  nickel  finish. 


No.  115  Rutenber  Range. 


The  frames  of  the  ranges  are  made  of  cast  iron  and 
the  sheet  metal  parts  of  blue  polished  steel. 

The  heating  elements  are  of  the  radiant  type,  con- 
sisting of  coils  of  wire   laid  in   grooves  of  a   special 


THE    ELECTRIC    RANGE 


61 


moulded  clay  compound.     Each  range  is  provided  with 
two  such  elements. 

The  ovens  are  heavily  insulated  with  rock  wool 
and   the   interior   walls   are   made   of  a   special   alloy. 


RUTENBER   RANGES. 

lype. 

style. 

Cooking 
No.  of 
Elements. 

Surface. 
Watta-e. 
(of  Each) 

Total 

Wattage 

of  Range. 

No. 

Wattage. 

Dimensions. 

105 

Low 

2-1000 

18x18x14 

4 

1000 

6000 

110 

Low 

2-800 

18x18x14 

3 

1000 

4600 

115 

Low 

2-800 

18x12x14 

2 

1000 

3600 

The  doors  open  to  the  side,  are  heavily  latched  to  pre- 
vent the  loss  of  heat,  and  are  fitted  with  standard 
oven  thermometers. 

Acorn  Ranges. — Rathbone  Sard  &  Company,  which 
has  been  the  maker  of  the  well-known  Acorn  fuel 
ranges  for  many  years,  has  recently  taken  up  the  man- 


ufacture of  electric  ranges.  It  now  has  a  line  of  these 
new  ranges,  consisting  of  two  low  oven  types  and 
five  cabinet  types.  It  will  be  noted  that  the  low  oven 
types  are  the  same  except  that  one  has  three  surface 
elements,  whereas  the  other  has  four.  The  cabinet 
type  ranges  have  the  same  number  of  surface  elements, 


62 


ELECTRIC    HEATING 


ACORN    RANGES. 

1 

Xo. 
El 

■yi>o. 

St.vle. 
Low 

Oven 

Cooking 

Surface. 
Wattage 
(of  Eacli) 

1000 

Total 
Wattage 
of  Range. 

5500 

Wattage. 
1-1500 
1-1000 

Dimensions.      Elements. 
18x14x18      3-101/^  in. 

E5 

Low 

1-1500 
1-1000 

18x14x18 

4-101/2  in. 

1000 

6500 

ElO 

Cabinet 

1-1500 
1-1000 

18x14x18 

4-101/2  in. 

1000 

Plate 

warmer 

18x10x18 

6500 

E20 

Cabinet 

1-1500 
1-1000 
1-1500 

18x14x18 
18x10x18 

4-101/2  in. 

1000 

8000 

E30 

Cabinet 

1-1500 
1-1000 
1-1500 

18x14x18 
18x10x18 

4-101/2  in. 

1000 

Plate 

warmer 

18x10x18 

8000 

E40 

Cabinet 

1-1500 
1-1000 

18x14x18 

Plate 

warmer 

18x10x18 

4-101/^  in. 

1000 

6500 

EoO 

Cabinet 

1-1500 

1-1000 

Warmer 

18x14x18 
18x10x18 

■i-lOMi  in. 

1000 

Plate  shelf 

18x10x18 

6500 

the  same  dimension  and  capacity  baking  and  warming 
ovens,  and  occupy  the  same  floor  areas.  The  frames 
are  made  of  cast  iron  and  the  sheet  metal  parts  of 
heavy  gauge  iron.  They  are  finished  plain  or  equipped 
with  white  enameled  splashers  and  nickel  trimmings. 

The  ovens  are  lined  with  a  special  heat  insulating 
material  known  as  "duro-therm."  They  are  provided 
with  white  enameled  doors  and  broiler  pans.  The 
doors  are  also  equipped  with  thermometers  and  posi- 
tive tight  closing  latches. 

The  heating  elements  of  the  cooking  surfaces  are 
the  standard  General  Electric  sheathed  wire  enclosed 
types,  whereas  the  oven  units  are  the  sheathed  wire 
radiant  types.  Two  hundred  watt  vegetable  cookers 
may  be  substituted  for  any  one  of  the  surface  cooking 
elements. 

Standard  Ranges. — The  Standard  Electric  Stove 
Company,  successors  to  the  Detroit  Fireless  Stove 
Company,  has  developed  a  line  of  electric  ranges  which 
is  different  from  other  makes  in  several  particulars. 
The  ranges  are  made  of  Armco  iron,  finished  in  blue 
enamel,  and  nickel  trimmed.  The  ovens  and  cooker 
pots  are  thoroughly  insulated  with  rock  wool,  and  lined 
with  aluminum. 


THE    ELECTRIC    RANGE 


63 


The  compartments  are  mounted  with  the  covers 
even  with  the  cooking  surface.  These  covers  are 
hinged  at  the  back  and  provided  with  locking  devices. 
The  compartments  and  surface  heating  elements  are 


^^j|^^^H 


standard  No.  500  Range. 

mounted  side  by  side  in  a  line  parallel  with  the  front 
of  the  stove.  The  ovens  are  mounted  above  the  cook- 
ing surface  and  fitted  with  plate  glass  doors. 

The  oven  elements  are  of  the  radiant  type.     The 
compartment  and  surface  heating  elements  are  of  the 


STANDARD  RANGES. 

No, 

Type 
Style. 

Cooking 
No.  of 
Elements. 

Surface. 
Wattage 
(of  Each) 

Total 

Wattage 

of  Range. 

Wattage. 

Dimensions. 

300 

Low  cooker 

1-660 

cooker 

2 

1000 

2660 

400 

Low  cooker 

2-660 

cooker 

2 

1000 

3320 

500 

Hig-h   oven 
Low  cooker 

2-800 
1-660 

11x12x161/2 
cooker 

2 

1000 

4260 

501 

High   oven 
Low  cooker 

2-1000 
1-660 

11x12x19 
cooker 

2 

1000 

4660 

600 

High  oven 
Low  cookers 

2-800 
2-660 

11x12x161/2 
cookers 

2 

1000 

4920 

601 

High   oven 
Low  cookers 

2-1000 
2-660 

11x12x19 
cookers 

2 

1000 

5320 

64  ELECTRIC    HEATING 

enclosed  type,  consisting  of  resistance  wires,  baked  in 
a  special  cement  composition  which  is  backed  up  with 
an  iron  shell. 

The  high  oven  types  are  provided  with  an  auto- 
matic device  which  may  be  set  to  turn  the  current  off 
after  the  food  has  cooked  a  certain  length  of  time. 
Control  switches  and  pilot  lamps,  mounted  on  the 
frame  of  the  ranges,  are  also  desirable  features. 


Garland  No.    26   Range. 

Garland  Ranges.- — The  Michigan  Stove  Company, 
one  of  the  larger  manufacturers  of  fuel  stoves  has  re- 
cently placed  a  new  line  of  electric  ranges  on  the  mar- 
ket which  are  somewhat  different  from  other  makes 
of  electric  stoves.  They  are  made  up  by  various  com- 
binations of  interchangeable  parts  in  much  the  same 
way  as  sectional  book  cases.  The  cast  iron  frame  and 
sheet  steel  parts  are  coated  with  black  enamel,  and 
the  bright  parts  are  nickeled.  Doors,  broiler  pans, 
and  splashers  are  also  white  enameled. 

The  heating  elements  consist  of  resistance  ribbons, 
wound  on  mica  cores,  and  incased  in  sheet  steel  covers, 
forming  flat  strips  or  bars  %  in.  in  width.  Six  of 
these  strips,  each  of  200  watts  capacity,  are  mounted 


THE    ELECTRIC    RANGE 


65 


side  by  side  to  form  a  heating  unit.  These  units  or 
grids  are  separately  fused  and  located  on  top  of  hinged 
plates.  The  cooking  tops  are  built  with  either  two  or 
three  grids.  The  special  indicator  switches  which  are 
mounted  on  the  grids  are  very  desirable  as  their 
positions  may  be  determined  at  a  glance. 

The  oven  is  of  a  single  standard  size  and  may  be 
used  alone,  or  made  a  part  of  several  combinations 
with  the  grid  tops.  The  aluminized  steel  inner  wall 
is  surrounded  with  an  inch  air  space,  which  is  in  turn 
insulated  with  an  inch  of  special  material.     The  dou- 


GARI^AND  RANGES. 


Type. 

Style. 

Cooking 
No.  of 
Elements. 

Surface. 
Wattage 
(of  Each) 

TotPl 
Wattage 
of  Pange. 

No. 

Wattage. 

Dimensions. 

21 

Low 

2-1200 

18x12x12 

2 

1200 

4800 

23 

Low 

2-1200 

18x12x12 

4 

1200 

7200 

25 

2-Low 

4-1200 

18x12x12 

6 

1200 

12000 

26 

Cabinet 

2-1200 

18x12x12 

2 

1200 

4800 

27 

High 

2-1200 

18x12x12 

2 

1200 

4800 

28 

Low 

2-1200 

18x12x12 

4 

1200 

7200 

31 

Low 

2-1200 

18x12x12 

3 

1200 

6000 

33 

Low 

2-1200 

18x12x12 

6 

1200 

9600 

36 

Cabinet 

2-1200 

18x12x12 

3 

1200 

6000 

ble  door  is  made  up  in  much  the  same  way  as  the  oven 
walls  and  is  provided  with  a  tight  latch.  Broiling  is 
performed  in  the  oven  by  placing  the  meat  on  adjust- 
able pans,  which  press  it  against  wire  bars  below  the 
grids. 

Hotpoint  Ranges. — After  many  years  successful 
experience  in  the  production  and  marketing  of  lamp 
socket  heating  devices  the  Hotpoint  Electric  Heating 
Company  has  extended  its  efforts  to  the  construction 
of  electric  ranges.  The  five  types  of  ranges  now  man- 
ufactured are  made  of  cast  iron  and  sheet  steel.  They 
are  attractively  designed  and  trimmed  in  nickel  and 
white  enamel. 

The  ovens  are  heavily  insulated  with  mineral  wool. 
The  doors  latch  tightly  and  may  be  fitted  with  glass 
if  desired.  The  lining  of  the  ovens  is  made  of  alum- 
inized steel. 

The  cooking  surfaces  are  hinged  at  the  back,  thus 
permitting  easy  access  for  inspection  or  repairs.     The 


66 


ELECTRIC    HEATING 


heating  elements  are  of  the  open  coil  radiant  type, 
mounted  above  polished  concave  reflectors  which  col- 
lect the  heat  rays  passing  downward  and  direct  them 
backward  against  the  utensils.  The  reflectors  are 
mounted  on  the  crumb  trays  below  the  cooking  sur- 
faces, and  may  be  easily  removed  for  cleaning. 


HOTPOINT    RANGES. 


No. 

Type. 

Style. 

Waflage. 

Cooking 

—Oven No.  of 

Dimensions.      Elements. 

Surface. 
Wattage 
(of  Each) 

Total 
Wattase 
of  Range. 

D 

Cabinet 

2-1200 

181/2x181/2x12           1 
*18i^xl8xl0            1 

1500 

1200 

800 

6,700 

E 

Cabinet 

2-1000 

16  1/2x1 6 1/2x1 11/2      1 
*12i/2Xl2i/^xlOi/2      1 

1500 

1200 

800 

5,500 

F 

High  oven 

2-1000 

181^x161/2X111/2         1 

1500 

1200 

800 

5,500 

G 

Low  oven 

2-1000 

181^x16x11%          1 

1500 

1200 

800 

5,500 

H 

Low  oven 
♦Warming 

2-1000 
closets. 

16x14x12               1 

1500 
800 

4,300 

Hot  Point  Range. 


Other  Types  of  Ranges. — The  recent  rapid  devel- 
opment of  the  electric  range  market  has  served  to 
arouse  latent  interest  in  their  production.  A  number 
of  manufacturers  of  electric  heating  devices  and  fuel 


THE     ELECTRIC     RANGE 


67 


I 


ranges  have  signified  their  intention  of  designing  and 
marketing  electric  ranges  in  the  near  future.  The 
effort  that  is  being  put  forth  by  the  central  stations 
and  manufacturers  to  popularize  and  create  a  market 
for  electric  ranges  must  result  in  improved  apparatus, 
standardization  of  design  and  eventual  lowering  of 
production  costs. 


CHAPTER  VI 

COMMERCIAL  COOKING. 

Opportunities   in    Hotels    and    Restaurants. — The 

substitution  of  electric  for  fuel  heating  apparatus  in 
hotels,  restaurants  and  institutions  presents  enor- 
mous commercial  possibilities.  Consideration  of  the 
opportunities  afforded  the  central  station  companies, 
and  the  manufacturers  of  heating  devices,  however, 
have  only  recently  been  given  favorable  attention.  The 
savings  and  other  advantages  accruing  to  the  cus- 
tomer, the  tremendous  possibilities  for  building  up 
attractive  central  station  loads,  and  the  ever  widening 
market  for  the  various  kinds  of  electric  heating  de- 
vices in  the  modern  hotels  and  restaurants,  make  the 
subject  one  of  mutual  interest  worthy  of  serious  con- 
sideration. 

Advantages  of  Electric  Cooking. — Most  of  the  ad- 
vantages already  cited  in  favor  of  electric  ranges  in 
the  home,  apply  to  the  use  of  electric  cooking  equip- 
ment in  commercial  enterprises  to  an  even  greater  ex- 
tent. The  absence  of  dirt,  smoke,  excessive  heat,  and 
poisonous  fumes,  the  advertising  value  of  the  clean 
sanitary  kitchen,  the  improvement  of  food,  and  the 
saving  in  floor  space,  fuel  storage  capacity,  and  meat 
shrinkage,  are  all  points  of  superiority  that  create  keen 
interest. 

Careful  Planning  Essential. — In  spite  of  the  ad- 
vantages of  electric  cooking  service  in  the  modern 
hotel  and  restaurant  kitchen,  many  failures  have 
occurred.  These  have  frequently  been  due  to  unwise 
selection  of  apparatus,  lack  of  appreciation  of  the 
users'  requirements,  or  the  adverse  attitude  of  a  cook 
or  chef.  A  careful  preliminary  study  of  each  individual 
condition  is  of  extreme  importance  if  success  is  to  be 
achieved. 


COMMERCIAL    COOKING 


69 


It  is  first  necessary  to  know  the  approximate  max- 
imum amount  and  kinds  of  food  that  will  be  served, 
how  long  a  period  will  be  allowed  in  which  to  serve 
them,  how  long  they  must  be  kept  warm,  etc.  It  is 
always  necessary  to  consider  maximum  conditions. 
Unlike  fuel  apparatus  electric  equipment  cannot  be 
forced  under  conditions  of  stress. 

The  attitude,  intelligence,  and  often  the  nation- 
ality of  the  cooks  who  actually  operate  the  apparatus 
is  worthy  of  serious  consideration.  The  care  and  skill 
with    which    electric    devices    are     manipulated,     have 


General  Electric  Ranges  and  Broilers  in  Bethlehem   (Pa.)   Steel 
Company's  Kitchen. 


much  to  do  with  their  successful  operation.  Many 
cooks  trained  by  long  experience  in  the  actual  prepa- 
ration of  food,  dislike  to  take  up  new  methods.  Others 
are  intellectually  unfitted  or  flatly  refuse  to  learn. 

Choice  of  Apparatus. — In  laying  out  an  installation 
it  must  be  remembered  that  the  equipment  will  be 
subjected  to  extremely  rough  usage.  Only  the  best 
and  most  substantial  apparatus  available  should  be  in- 
stalled. It  should  be  designed  for  easy  control.  The 
cooking  surface  of  the  range  should  be  of  adequate 
capacity   because   much   top   cooking   is   done   in    the 


70 


ELECTRIC    HEATING 


average  hotel  or  restaurant.  A  few  extra  capacity 
units  for  rapid  work  are  usually  required.  Prelimi- 
nary advice,  as  to  the  kind  of  utensils  that  will  give 
the  quickest  and  most  efficient  results,  will  also  be 
helpful  to  the  user. 

Shrinkage  in  Meats. — The  tendency  to  minimize 
the  importance  of  meat  shrinkage  by  the  management 
of  hotels  and  restaurants  is  very  general,  but  never- 
theless such  losses  are  worthy  of  serious  considera- 
tion. The  enormous  v^aste  resulting  from  the  ordinary 
fuel  methods  of  preparing  meats,  coupled  with  its  high 


Special   Hughes   Cooking  Surface   and   Standard   Meat   Roasting 
Oven  in  Cafeteria,  Sacramento,  Cal. 


cost  and  serving  value,  make  the  savings  effected  by 
the  application  of  electrical  methods  of  real  importance, 
especially  where  large  quantities  of  meat  are  cooked 
daily. 

To  those  who  have  actually  observed  meats  pre- 
pared by  both  fuel  and  electric  means  the  saving  is 
obvious.  A  great  many  actual  tests  have  been  made, 
and  universally  the  results  have  shown  a  marked  sav- 
ing in  favor  of  electricity.     The  following  table  is  a 


I 


COMMERCIAL    COOKING  71 

compilation  of  experiments  made  by  Mr.  K.  B.  Mat- 
thews of  England  in  the  preparation  of  beef  and  mut- 
ton with  coal,  gas,  and  electricity: 

Weight  Weight 

before               after           Type  Loss  of  Loss 

cooking.         cooking.           of  weight.  per 

lb.        oz.        lb.       oz.         Oven  lb.       oz.  cent. 

Ribs    of    beef 5          7          3        12        Coal  1        11  31.0 

Leg   of   mutton 8          8          5        13       Coal  2        11  31.7 

Shoulder  of  mutton.  .  .    6        13          5          1        Coal  1        12  25.7 

Leg  of  mutton 8          4          6          0        Gas  2          4  28.1 

Leg   of    mutton 9          0          7        12        Elec.  1          4  13.1 

Shoulder  of  mutton.  .  .    4        12          4          2        Elec.  0        10  13.1 

Ribs    of   beef 9          17          6        Elec.  1        11  18.6 

Leg   of   mutton 9          1          7        10        Elec.  1          7  15.8 

Shoulder  of  mutton.  .  .    5        10          5          0        Elec.  0        10  11.1 


General  Electric  Ranges  in  Galley  of  U.  S.  S.  Texas. 


Apparatus  Available. — Only  a  few  manufacturers 
of  electric  heating  devices  in  this  country  have  under- 
taken the  extensive  production  of  commercial  cooking 
apparatus.  There  are  several  reasons  for  this  condi- 
tion. Development  work  is  expensive  and  the  market 
for  the  equipment  has,  until  recently  been  limited. 
Only  such  apparatus  as  will  "stand  up"  under  the 
severest  kind  of  operating  conditions  ever  proves  sat- 
isfactory. The  rather  sad  experience,  which  some  con- 
cerns have  had  in  attempting  to  utilize  the  less  rugged 


72 


ELECTRIC    HEATING 


types  of  domestic  cooking  devices  for  hotel  and  res- 
taurant service,  has  exerted  a  somewhat  discouraging 
efifect  on  further  development. 

There  is  no  doubt,  however,  but  that  the  experi- 
ence gained  thus  far,  has  been  valuable.  The  types 
of  apparatus  that  have  stood  the  test  have  been  ex- 
tremely satisfactory  to  the  users,  and  now  that  so 
many  improvements  have  been  made  in  the  design 
of  heating  apparatus,  there  is  no  question  but  the 
market  will  develop  rapidly  and  result  in  quantity  pro- 
duction and  further  price  reduction. 


General  Electric  Type  D-54  Range  in  Dietary  Kitchen  in  Penn- 
sylvania State  Hospital,  Philadelphia,  Pa. 


As  quite  a  few  types  of  apparatus  designed  ex- 
clusively for  commercial  cooking  service  are  now  avail- 
able, some  of  the  features  of  those  best  known  will 
be   described. 

Hotel  Ranges. — No  other  piece  of  kitchen  equip- 
ment is  subject  to  such  severe  treatment  as  the  hotel 
or  restaurant  range,  especially  the  top  cooking  sur- 
face. Earlier  installations  were  either  too  frail,  too 
small,  or  too  slow  in  heating  to  give  satisfaction.  The 
modern     types,     however,     are     heavily     constructed, 


COMMERCIAL    COOKING  73 

available  in  adequate  capacities,  and  generally  pro- 
vided with  sufficient  wattage  in  the  heating  units  to 
perform  work  quickly. 

General  Electric  Hotel  Range. — This  type  of  range 
is  constructed  of  heavy  cast  iron,  and  steel  sheet 
metal.  The  oven  walls  are  well  insulated  with  navy 
firefelt.  The  cooking  surfaces  are  composed  of  eight 
oblong  9^  by  12  in.  enclosed  type  cast  iron  heating 
units,  placed  side  by  side,  arranged  with  four  1600 
watt  units  in  front  for  high  temperature  cooking,  and 
with  four  800  watt  units  in  back  for  lower  temperature 
work. 

There  are  two  ovens,  each  having  a  capacity  of 
4800  watts,  and  inside  dimensions  of  18  in.  width,  28 
in.  depth  and  16  in.  height.  The  doors  are  heavily 
constructed  and  are  of  the  drop  type.  All  the  heating 
units  are  fused  and  controlled  by  knife  switches  located 
in  a  sheet  metal  compartment  above  and  at  the  rear 
of  the  cooking  surface. 

The  overall  dimensions  of  the  range  are  width 
44  in.,  depth  38  in.  and  height  to  top  of  switch  box 
68  in.  The  maximum  rated  capacity  is  19.2  kilowatts. 
An  equipment  sufficiently  large  to  take  care  of  any 
requirements  can  be  provided  by  placing  as  many  of 
these  ranges  side  by  side  as  are  necessary. 

Simplex  Hotel  Ranges. — The  high  duty  ranges 
manufactured  for  hotel  and  restaurant  service  are  made 
of  much  heavier  materials  than  those  designed  for 
domestic  use.  The  parts  are  constructed  of  heavy 
gauge  steel  and  cast  iron.  The  general  appearance 
is  much  the  same  as  that  of  the  more  elaborate  hotel 
fuel  ranges.  They  are  ordinarily  made  up  in  complete 
sections  consisting  of  a  cooking  surface  7  ft.  6  in.  long 
by  2  ft.  9  in.  wide,  with  two  ovens  mounted  beneath. 
For  very  large  installations,  two  or  more  of  these 
sections  are  placed,  end  to  end,  or  back  to  back. 

The  cooking  surface  is  usually  made  up  to  suit 
the  customer's  requirements.  The  units  may  consist 
of  any  suitable  arrangement  of  the  following  heating 
elements  in  various  capacities : 


74 


ELECTRIC    HEATING 


Rim  or  flat  griddles,  9  in.  by  12  in.,  12  in.  by  18  in.  or  18  in.  by 

24    In.   sizes. 
Hotel  broilers,   9  in.   by  12   in.,  or  12  in.  by  18   in.  sizes. 
Disc  stoves  4i/^    in.  diameters   to   20   in.  diameters   together  with 

special   heavy   copper   kettles  and   other   utensils   of   similar 

dimensions. 
Deep  fat  frying  kettles — 12  in.  diameter,  5  in.  deep. 
Hotel    toasters — 10   in.    by    12    in.,   or   12   in.   by    18    in.    sizes. 
Waffle  irons — two  or  three  section    (for  4  V^    in.   waffles.) 


Simplex 


•ovtn    Range,    ^V'eit■a^e    DiUtng   Hall,    Kdison    Electric 
Illuminating  Company,   Boston. 


The  ovens  are  of  heavy  construction,  well  insu- 
lated  and   provided    with   massive    drop    doors.      The 


Foi 


■tion   Simplex  Range,  Montana  State  Hospital,  Billings. 


interior  dimensions  are  24  in.  wide,  27  in.  deep,  and 
16  in.  high.  The  oven  heaters  are  located  in  both 
the  top  and  bottom. 


i 


COMMERCIAL    COOKING 


75 


Kach  range  section  is  supplied  with  a  distributing 
panel,  located  between  the  ovens  and  accessible  from 
the  front.  The  circuits  are  separately  fused,  and  each 
device  has  its  own  control  switch,  and  pilot  light. 

Meat  Broilers. — Two  types  of  broilers  are  made 
— the  open  type  and  the  enclosed  type.     It  is  safe  to 


Hughes  Meat  Broiler. 

say  that  better  results  can  be  secured  with  either  of 
these  types  than  are  attainable  with  any  kind  of  fuel 
broiler. 

The   Simplex  open  type  apparatus   consists  of  a 
corrugated  cast  iron  surface  slanting  slightly  towards 


76 


ELECTRIC    HEATING 


a  grooved  end.  The  meat  rests  on  the  hot  surface 
and  the  juices  are  collected  at  the  mouth  of  the 
groove  and  poured  over  the  meat  before  serving.  The 
heating  is  done  by  means  of  a  sealed-in  unit  under 
the  corrugated  surface.  The  standard  hotel  size  is 
12  in.  by  18  in.  and  has  a  capacity  of  2200  watts. 

The  Hughes  Broiler  is  of  the  enclosed  type  and 
is  manufactured  in  three  standard  sizes.  The  smaller 
size  has  interior  dimensions  of  18  in.  by  30  in.  by  8  in. 
and  has  a  capacity  of  4.5  kilowatts.  The  medium  size  is 
composed  of  two  compartments  placed  side  by  side, 
each  having  the  same  dimensions  and  capacity.  The 
large  size  is  32  in.  by  30  in.  by  8  in.  and  has  a  capacity 
of  10  kilowatts.  The  walls  of  these  broilers  are  heavily 
insulated.  The  units  are  of  the  open  type  and  give 
off  radiant  heat.  The  exteriors  are  finished  in  black 
iron,  and  the  bodies  are  supported  on  angle  iron 
frames. 

The  General  Electric  broiler  is  of  the  enclosed  type 
and    equipped    with    radiant    heating   elements.      The 


General   Electric  Meat  Broiler. 


broiling  area  is  14  in.  by  20  in.  The  rated  capacity 
is  5  kilowatts,  of  which  4.5  kilowatts  is  used  during 
actual  operation  and  500  watts  for  maintaining  the 
temperature  when  the  device  is  not  in  service.     It  is 


COMMERCIAL    COOKING 


77 


made  of  heavy  sheet  steel  and  angle  iron  construction 
and  the  walls  are  thoroughly  insulated.  It  is  mounted 
on  angle  iron  supports. 

Hot  Closets. — Hot  closets  are  required  in  almost 
every  hotel  and  restaurant  kitchen  for  keeping  food 
and  dishes  warm.  They  generally  consist  of  double 
walled  or  well-insulated  ovens  with  oue  or  more 
shelves,  doors  opening  to  the  side,  and  equipped  with 


Cutler-Hammer  Hot  Closet. 


relatively  small  heating  units  mounted  in  the  bottom. 
They  are  usually  provided  with  three-heat  control 
switches.  The  Hughes  and  Simplex  warming  ovens 
are  made  up  in  several  standard  sizes  but  may  be  de- 
signed in  any  special  size  or  capacity. 

Steam  Tables. — When  food  must  be  kept  warm 
for  any  length  of  time  for  serving,  a  steam  table  is 
usually  considered  a  necessity.  Either  immersion 
or  circulation  heaters  may  be  used  for  this  purpose. 

Immersion  heaters  may  be  inserted  through  the 
top  or  in  the  side  of  the  steam  table.     They  must  be 


78  ELECTRIC    HEATING 

kept  covered  with  water  constantly,  or  the  elements 
will  burn  out. 

Circulation  heaters  of  various  types  may  be  util- 
ized in  heating  a  steam  table  by  connecting  them  with 
pipes  to  the  bottom  of  the  tank  and  placing  the  heat- 
ers at  an  angle  of  about  10°  to  15°  with  the  horizontal. 
The  colder  water  reaching  the  lower  end  of  the  heater 
will  rise  in  temperature  and  gradually  pass  up  through 
the  heater  into  the  tank,  thus  creating  a  constant  cir- 
culation and  gradual  heating  of  water  as  long  as  the 
current  is  applied. 


'Neuco"  steam  Table. 


It  is  essential  that  steam  tables  be  well  insulated 
against  heat  losses.  If  the  circulation  method  of  heat- 
ing is  employed,  the  pipes  leading  to  and  away  from 
the  heater  should  be  well  lagged. 

In  making  calculations  of  the  heater  capacity  re- 
quired for  a  steam  table,  area  of  radiating  surface, 
kind  and  thickness  of  lagging,  nature  of  top  surface, 
amount  of  water  in  reservoir,  hours  of  use,  and  the 
maximum  quantity  of  food  warmed,  should  be  taken 
into  consideration. 

Water  Heaters. — A  supply  of  hot  water  for  cook- 
ing, dish  washing  and  various  other  purposes  must 
always  be  provided  in  the  hotel  or  restaurant  kitchen. 
The  subject  of  heating  water  electrically  is  taken  up 


COMMERCIAL    COOKING 


79 


more  fully  in  another  chapter,  but  it  is  well  to  keep 
in  mind  that  the  demand  for  hot  water  is  usually  much 
in  excess  of  most  chefs'  or  cooks'  preliminary  estimates. 

Frying  Kettles. — Fat,  oil,  or  lard  is  often  required 
to  be  heated  to  a  high  temperature  for  preparing 
French  fried  potatoes,  doughnuts,  croquettes,  and 
other  foods. 

The  Simplex  frying  kettle  designed  for  heavy 
service  has  standard  dimensions  of  12-inch  diameter 
and  5-inch  depth.     It  has  a  maximum  rated  capacity 


simplex  Frying  Kettle. 

of  2400  watts  and  is  provided  with  a  three-heat  con- 
trol switch.  Larger  sizes  are  sometimes  manufactured 
for  special  work. 

Toasters. — Some  provision  for  toasting  bread 
evenly  and  quickly  is  required  in  all  hotel  and  restau- 
rant kitchens.  A  high  heat  is  required  and  the  device 
must  do  the  work  rapidly,  or  the  toast  will  be  dry  and 
hard. 

The  General  Electric  radiant  type  toaster  has  a 
capacity  of  two,  three,  or  six  slices  of  toast,  during 
the  preparation  of  which  1350  watts,  1800  watts,  and 


80 


ELECTRIC    HEATING 


General    Electric    Hotel    Toaster 


3150  watts,  respectively  are  connected.  The  sides, 
base,  and  back  of  the  device  are  of  sheet  iron.  The 
top  and  front  are  open.  The  heating  coils,  of  which 
there  are  seven,  are  placed  at  each  end  and  between 
the  hinged  wire  racks  that  support  the  slices  of  bread. 
Each  rack  is  separately  hinged  to  facilitate  the  removel 


Hughes  Hotel  Toaster. 


or  examination  of  individual  slices. 

The  Plughes  toaster  is  of  the  oven  type.  The 
toast  is  placed  on  a  rack  measuring  8  inches  by  18}^ 
inches  and  inserted  within  the  sheet  iron  casing  be- 
tween    radiant    type    heating    elements.     The    rated 


COMMERCIAL    COOKING 


81 


capacity  is  2  kilowatts.  The  outside  dimensions  of 
the  device  are  9^  inches  wide,  19  inches  deep,  and  9 
inches  high.  Sixteen  slices  of  bread  may  be  toasted 
at  one  time.  As  the  operation  is  performed  within  the 
casing  the  heat  is  conserved  to  a  marked  extent. 

The  Simplex  toaster  consists  of  an  oblong  fiat  top 
griddle  on  which  the  bread  is  placed  and  provided 
with  either  one  or  two  grids,  hinged  at  the  back,  which 
are  folded  down  upon  the  upper  surface  of  the  bread, 


Cutler-Hammer  Coffee  Urn. 


thereby  toasting  both  sides  of  the  slices  simultane- 
ously. The  device  is  made  in  two  sizes.  The  smaller 
one  is  10  inches  by  12  inches  and  has  a  rated  capacity 
of  1000  watts.  The  larger  one  is  12  inches  by  18 
inches  and  is  rated  at  1700  watts.  Both  sizes  are 
equipped  with  three-heat  switches  and  so  connected 
that  the  bottom  griddle  may  be  heated  separately  for 
baking  hot  cakes  and  similar  operations.  The  heating 
elements  are  of  the  enclosed  sealed-in  type. 


82 


ELECTRIC    HEATING 


Coffee  Urns. — Either  immersion  type  or  disc  type 
elements  may  be  used  for  heating  coffee  urns  in  a 
hotel  or  restaurant.  Electrically  heated  urns  of  ten 
gallons  capacity  or  larger,  provided  with  heating  units 
of  either  the  immersion  or  disc  type,  are  available. 
Some  of  these  urns  are  of  the  single  shell  type,  whereas 
others  are  double  walled  and  thoroughly  insulated. 
Some  are  of  the  spray  type  and  others  are  equipped 
with  stoneware  crocks  for  holding  the  coffee. 


Simplex  Hot  Cake  Griddle. 


The  rated  capacities  of  the  standard  single  shell 
type  urns  vary  from  about  1200  watts  for  a  two  gal- 
lon size,  to  about  4500  watts  for  the  ten  gallon  size. 
The  double  walled  types  are  much  to  be  preferred, 
however,  on  account  of  their  higher  operating  effi- 
ciencies. 

It  is  often  desirable  to  convert  a  fuel  burning  urn 
into  an  electrically  heated  device.  This  may  be  done, 
either  by  inserting  an  immersion  heater  of  the  proper 
design  in  the  top,  or  by  supporting  a  heating  element 
against  the  bottom  of  the  urn. 

Hot  Cake  and  Frying  Gridldes. — Flat  top  griddles 
for  making  hot  cakes  are  available  in  many  sizes  and 
makes.  The  18  inch  by  24  inch  Simplex  flat  top  grid- 
dle has  a  rated  capacity  of  2800  watts,  whereas  the 
frying  griddle  of  the  same  make  has  a  rated  capacity 
of  3300  watts. 

Frying  griddles  are  a  necessary  adjunct  to  the 
modern  hotel  and  restaurant  kitchen.  They  are 
usually  provided  with  raised  edges.     For  quick  frying 


COMMERCIAL    COOKING 


83 


of  eggs,  steaks,  and  fish  orders  they  are  convenient. 
Operated  on  medium  heat,  the  frying  griddles  may 
be  used  for  making  hot  cakes. 


Simplex  Frying-  Griddle. 

Waffle  Irons. — For  making  waffles  the  electrically 
heated  device  is  much  superior  to  those  heated  by 
fuel.  Little  grease  is  required.  The  waffles  are  evenly 
browned  and  very  attractive  and  palatable. 

The  Simplex  waffle  irons  are  made  in  two  sizes, 
adaptable  for  making  dther  two  or  three  4^  in. 
waffles  at  a  time,  and  of  rated  capacities  of  770  watts 
and   1150  watts  respectively.     They  are   so  designed 


Simplex  Two-Section  Waffle  Iron. 

that  the  sections  are  connected  in  series  when  heating 
up  and  in  parallel  when  the  waffles  are  baking.  This 
arrangement  makes  it  possible  to  keep  the  elements 
moderately  hot  between  operations,  and  very  hot  while 
the  waffles  are  cooking.  The  elements  are  of  the 
sealed-in  type  imbedded  in  the  iron.  The  frame  of  the 
device  is  of  heavy  cast  iron. 

Electric  Bake  Ovens. 

Extent  of  Use. — The  electric  bake  oven  is  being 
used  extensively  and  with  marked  success  in  a  num- 
ber of  western  cities  and  towns  as  well  as  in  some 


84  ELECTRIC    HEATING 

parts  of  the  east.  It  combines  efficiency,  speed,  econ- 
omy, and  durability.  It  has  found  widest  application 
in  small  bakeries,  hotels,  restaurants,  and  various 
institutions.  The  electric  bake  oven  is  a  compara- 
tively new  development,  and  its  possibilities  have  but 
recently  been  realized.  There  is  no  doubt,  but  what 
it  has  a  wide  field  of  usefulness,  and  will  eventually 
afford  a  desirable  load  for  central  stations  throughout 
the  country. 

Construction  of  Electric  Ovens. — Electric  ovens 
are  usually  constructed  in  the  cabinet  form,  with  from 
three  to  five  decks  or  compartments  built  one  above 
the  other.  This  design  is  unlike  the  brick  baker's  oven 
which  has  only  one  deck  but  is  somewhat  similar  to 
the  ordinary  portable  gas  oven.  The  exterior  walls 
are  generally  made  up  of  galvanized  sheet  iron  and 
the  space  between  the  exterior  and  interior  walls  filled 
with  a  thick  layer  of  mineral  wool  or  some  other  heat 
resisting  material. 

The  capacities  of  ovens  now  in  use  vary  from  30 
to  500  one-pound  loaves,  with  baking  surfaces  of  from 
10  to  160  square  feet,  and  with  heater  capacities  of  from 
4  to  65  kilowatts.  The  weights  of  these  ovens  vary 
from  700  to  10,000  pounds.  They  may  usually  be 
heated  to  the  proper  temperature  for  bread  baking 
in  from  40  to  60  minutes. 

There  are  two'  common  methods  of  heating  elec- 
tric ovens,  both  of  which  have  certain  advantages.  In 
the  styles  first  placed  on  the  market,  the  heating  ele- 
ments were  mounted  below  the  lower  deck,  and  the 
heat  circulated  upwards  along  the  sides  and  interior 
walls  which  were  so  arranged  as  to  properly  distrib- 
ute the  heat  at  each  deck.  The  General  Electric  and 
Simplex  ovens  are  made  in  this  way.  The  Hughes 
bake  oven,  however,  is  heated  by  coils  of  resistance 
wire  mounted  between  each  deck,  above  the  top  deck, 
and  below  the  bottom  deck.  Each  element  is  con- 
trolled by  a  three-heat  switch.  The  wattage  of  each 
element  is  a  little  greater  than  the  one  above  it,  and 
likewise,  the  front  part  of  each  deck  is  made  some- 
what   hotter     than    the    back.     These    provisions    are 


COMMERCIAL    COOKING 


85 


necessary  on  account  of  the  gradual  rise  of  heat  to 
the  top,  and  because  of  the  heat  losses  around  the  deck 
doors. 

Features  of  Electric  Ovens. — The  decks  are  ac- 
cessible through  hinged  drop  doors.  The  standard 
height  of  deck  is  about  eight  inches  but  they  may  be 
made  higher  if  necessary.  Tile  decks  may  be  used  for 
continuous  or  heavy  baking.  Ovens  so  equipped  will 
require  more  time  to  heat  up  but  will  maintain  the 
temperature  to  better  advantage  when  they  are  finally 
heated.  Ovens  not  provided  with  tile  decks  are 
usually  furnished  with  drip  pans. 

An  accurate  pyrometer  for  indicating  the  temper- 
ature should  always  be  made  a  part  of  the  oven  equip- 
ment. This  instrument  will  be  an  aid  to  economy 
of  operation  and  a  great  convenience  for  the  baker. 

Table  I. — Simplex  Bake  Ovens. 

Sq.  ft.  Height  Maximum 

No.  1-lb.            No.  of          of  Baking  of  Decks  kw. 

No.                   Loaves.             Decks.             Surface.  in  Inches.  Demand. 

152                     36                     3                     12                     8  6 

154                      56                      4                     18                      8  8 

156                      70                     5                     23                     8  9 

158                      90                     5                     26                     8  10 


Simplex  No.  156  Bake  Oven. 


Simplex  Ovens. — Four  standard  sized  ovens,  as 
shown  in  Table  I,  are  made  by  the  Simplex  Company. 
The  temperatures  in  the  ovens  are  controlled  by  single 


86 


ELECTRIC    HEATING 


three-heat  switches,  which  are  usually  fastened  to  the 
wall.  The  heating  elements  are  of  the  cast  grid  type 
mounted  in  the  base.  , 

General  Electric  Ovens. — Three  standard  ovens, 
as  shown  in  Table  II,  are  manufactured  by  the  Gen- 
eral Electric  Company.     They  are  of  the  Blodgett  type, 


General  Electric  Type  D-46  Bake  Oven. 


with  grid  resistance  heating  units  fitted  into  the 
base.  The  temperature  is  controlled  by  a  three-heat 
knife  switch,  which  may  be  mounted  in  any  convenient 
position. 


Table  II. — General    Electric    Bake    Ovens. 

No.  Sq.  ft  of  Dimensions  of 

1%-lb.  No.  of  Baking  Baking  Comp.  in  Inches. 

Type.         Loaves.  Decks.  Surface,  Width.      Depth.      Height. 

D-44              30  3            11.74  28  20            6.75 

D-46             56  4            21.11  38  20            6.75 

D-47             84  4            31.66  38  30            6.75 


Maximum 

kw. 
Demand. 


13 


Hughes  Ovens. — Ten  standard  ovens,  as  shown 
in  Table  III,  are  made  by  the  Hughes  Company.  The 
heating  units  are  mounted  between  the  decks,  and  each 


COMMERCIAL    COOKING 


87 


set  is  controlled  by  a  separate  three-heat  switch.  These 
ovens  may  be  manufactured  for  use  with  tile  decks 
when  desired. 


Hughes  No.   200   Bake   Oven. 


88 


ELECTRIC    HEATING 


Cat. 

No. 

150 

175 

200 

215 

220 

250 

300 

315 

400 

415 


No. 

1-lb. 

Loaves. 

30 

40 

63 

84 

126 

168 

192 

252 

378 

504 


Table  III HiiKhes 

Sq.  ft  of 


No.  of 
Depth. 

3 


Baking 
Surface. 
10 
13.5 
20.75 
27.75 
41 
54.5 
61.5 
82 

121 

161 


Bake    Oveus. 

Dimensions  of 

Baking  Comp.  in  Inches. 

Width.      Depth.      Height. 


18 
18 
37 
37 
37 
37 
37 
37 
73 
73 


27 
27 

27 
27 
53 
53 

80 
8(0 
80 
80 


Maximum 

kw. 
Demand. 
4 
5 
7.3 

10 

15 

20 

23.5 

31 

47 

62 


Advantages   of  Electric   Ovens.— The   many   fea- 
tures  of   superiority   of   electric   heat   over   fuel   heat 
which  apply  in   the  use   of  electric   ranges   obviously 
attend  its  use  in  connection  with  electric  baking  ovens 
A  baker's  shop  is  ordinarily  a  hot,  stuffy  place  because 


(    N  E  U  C  O  ) 

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1                         £-,-__   ^c^ 

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'Neuco-  No.   107  Bake  Oven    (Capacity  48  2-lb.  Loaves 


ELECTRIC  WATER  HEATING 


89 


of  the  intense  heat.  Very  little  radiation  of  heat, 
however,  is  noticeable  from  the  electric  oven  on 
account  of  its  heavy  insulation.  The  hand  may  be 
held  against  the  outside  with  no  discomfort  after  the 
oven  has  been  in  service  several  hours. 

Heat  Regulation. — The  heat  regulation  in  an  elec- 
tric oven  is  nearly  perfect.    It  is  an  obvious  advantage 


Hug-hes   No.    300   Bake   Oven,   Installed   in   Bakery   and   Grocery, 
Norfolk,  Va. 


to  be  able  to  obtain  the  desired  temperature  in  an  oven 
in  a  short  period  of  time.  This  feature  alone  goes  a 
long  way  toward  insuring  satisfactory  results. 

With  coal  ovens  it  is  necessary  to  have  a  contin- 
uous fire  in  order  that  they  may  be  put  in  operation 
without  delay.  Sometimes  only  one  or  two  batches 
of  bread  are  baked  during  the  night  but  the  fire  must 
be  kept  up  to  take  care  of  the  next  day's  business. 
The  electric  oven  overcomes  this  objection  as  it  can 
be  heated  quickly.  If  the  oven  is  not  used  contin- 
uously it  may  be  maintained  at  baking  temperature 
on  the  low  heat  with  one-quarter  the  maximum  current 
consumption. 


90  ELECTRIC     HEATING 

Saving  in  Floor  Space. — Only  a  fraction  of  the 
floor  space  is  required  for  an  electric  oven  that  is 
necessary  for  a  brick  oven.  The  user  of  a  brick  oven, 
furthermore,  must  have  a  large  space  in  front  of  his 
oven  in  which  to  manipulate  his  peel  for  inserting  and 
removing  material.  Very  small  space  for  this  pur- 
pose is  required  by  the  user  of  an  electric  oven.  The 
use  of  coal  ovens,  moreover,  makes  it  necessary  to 
provide  storage  space  for  a  large  supply  of  fuel.  Coal 
must  also  be  paid  for  in  advance  and  a  considerable 


Hughes  500-Ijoaf  Oven  (Special  Design). 

amount  of  money  is  tied  up.  No  storage  space,  how- 
ever, is  required  for  electric  energy,  and  it  is  not  paid 
for  until  used. 

When  a  new  bakery  is  constructed  it  may  be  made 
of  lighter  material,  because  electric  ovens  weigh  only 
a  fraction  as  much  as  brick  ovens. 

Sanitary  Features  of  Electric  Ovens. — Electric 
ovens  are  absolutely  sanitary.  The  heat  is  derived 
from  resistances  operating  at  comparatively  low  tem- 
peratures. There  are  no  fumes  or  objectionable  odors 
such  as  are  produced  by  gas  ovens,  to  contend  with. 
The  dirt  and  dust  always  encountered  with  brick  ovens 
are  entirely  obviated.  The  electric  ovens  may  also 
be  easily  and  quickly  cleaned. 


COMMERCIAL     COOKING 


91 


The  fact  that  an  electric  oven  is  used  in  a  place 
of  business  is  an  advertisement  for  the  establishment. 
It  carries  an  appeal  to  the  public  generally. 

Diversity  of  Baking. — All  classes  and  kinds  of 
bread,  cake,  cookies,  pies,  pie  shells,  patty  shells,  and 
rolls  may  be  baked  in  the  electric  oven  with  the  great- 
est satisfaction  and  ease,  and  at  a  very  reasonable  cost. 
Patty  shells  will  attain  the  beautiful  brown  and  flaky 
appearance  in  an  electric  oven  without  the  use  ot  Ggg 


BK  MIDNICKT  """" 

Typical  Load  Curve  Hughes  Special  500-L.oaf  Oven,  Turning  Out 
560   141/^-oz.   Loaves   Every   45   Minutes. 


and  butter  mixtures  that  are  usually  required  in  other 
ovens.  Bread,  cake  and  pies  will  always  have  just 
the  right  shape  and  color.  They  will  likewise  remain 
fresh  longer,  as  less  moisture  is  removed  from  the 
product. 

A  larger,  better  colored,  finer  textured,  and  thin- 
ner crusted  loaf  of  bread  can  be  produced  in  the  elec- 
tric, than  in  the  fuel  oven.  The  light  golden  brown 
color  of  bread  baked  electrically  will  always  increase 
the  demand  for  the  product. 

Cakes,  cookies,  etc.,  which  require  lower  temper- 
atures than  bread,  can  be  baked  after  the  bread  is  taken 
from  the  oven  without  using  additional  current,  or 
they  may  be  baked  while  the  oven  is  heating  up. 

Economy  in  Roasting  Meats. — The  great  variety 
of  food  that  may  be  prepared  in  an  electric  oven,  makes 


92  ELECTRIC     HEATING 

it  of  considerable  value  for  cafe,  cafeteria,  hotel,  and 
restaurant  use.  All  kinds  of  meats,  including  fish  and 
fowl,  may  be  roasted  in  an  electric  oven  with  less 
shrinkage  than  in  any  type  of  fuel  oven.  The  shrink- 
age loss  in  fuel  ovens  varies  from  30  to  40  per  cent, 
whereas  it  is  only  from  15  to  20  per  cent  in  the  elec- 
tric oven.  The  meats  will  always  be  juicy,  wholesome, 
clean,  attractive,  and  delicious  in  flavor.  No  oxygen 
being  consumed  or  poisonous  gases  being  given  off  in 
the  electric  oven,  the  meats  do  not  take  on  the  hard, 
bitter  tasting  crust  often  apparent  where  fuel  is  used. 

In  roasting  chickens  in  the  electric  oven  it  is  not 
necessary  to  spread  a  greased  cloth  over  them  to 
prevent  the  formation  of  hard  crusts.  They  will  be 
juicy  and  palatable  if  cooked  in  an  open  pan. 

Utilizing  Stored  Heat. — After  the  day's  cooking  is 
done,  cereal,  baked  apples,  baked  pork  and  beans, 
spiced  ham,  etc.,  can  be  prepared  in  electric  ovens 
without  using  any  additional  current.  Simply  place 
the  materials  in  the  oven.  They  will  cook  on  the 
stored  heat  and  be  readv  to  serve  for  breakfast. 


CHAPTER  VII 

ELECTRIC  WATER  HEATING. 

Hot  Water  a  Necessity. — Enormous  quantities  of 
energy  are  constantly  required  for  heating  water.  In 
the  average  home,  more  energy  is  used  for  heating 
water  than  for  any  other  domestic  purpose  aside  from 
that  utilized  in  warming  the  air.  In  the  industrial 
field,  the  operations  that  require  hot  water  are  almost 
without  number. 

For  generations  the  only  way  of  heating  water  has 
been  by  fuel  combustion  methods  whereby  chemical 
energy  stored  in  fuel  is  transformed  into  heat  energy, 
which  is  in  turn  taken  up  by  the  water  in  amounts 
varying  with  the  efficiency  of  the  apparatus  employed. 

Comparison  of  Fuel  and  Electricity. — As  set  forth 
in  another  chapter,  most  fuels,  on  the  basis  of  actual 
cost  of  the  two  mediums,  have  a  higher  heating  value 
than  electricity.  It  is  possible,  however,  to  operate 
an  electric  water  heater  at  a  much  higher  efficiency 
than  a  fuel  heater.  If  necessary,  the  electric  heater 
may  be  immersed  in  the  liquid  itself,  in  which  case 
practically  all  the  heat  generated  must  be  imparted 
directly  to  the  water.  This  is  impossible  with  a  fuel 
device  which  requires  that  external  heat  be  applied. 
It  is  obvious  that  fuel  heat  generated  on  the  outside 
of  a  tank  must  lose  much  useful  energy  through  the 
chimney  and  the  surrounding  atmosphere. 

Although  it  should  not  be  understood  that  elec- 
tricity for  heating  water  can  compete  on  a  cost  basis 
with  the  many  cheap  fuels  that  are  available  in  most 
localities,  it  should  be  known  that  it  is  often  possible 
to  so  design  electrical  installations  that  they  will  not  be 
more  expensive  to  operate  than  the  less  efficient  fuel 
burning  devices  that  are  commonly  used.  This  condi- 
tion is  especially  true  with  the  smaller  installations. 


94 


ELECTRIC     HEATING 


In  making  comparisons  between  fuel  and  electric 
water  heating  methods,  the  many  advantages  of  elec- 
tric operation,  aside  from  the  cost,  should  be  consid- 
ered. Dirt,  smoke,  moisture,  fumes,  and  excessive  heat 
are  obviated  when  the  electric  method  is  used.  The 
dangers  of  fire  and  explosions  are  done  away  with. 
The  care  and  attention  required  by  fuel  burning  appa- 


CtRCvmriON  TYPt 
HZMLR 


IMMEKSIOH  TYP£ 
HEATER 


fTTANK^W: 


MldTFH 


CIRCULATION  TYPE 
HEATEP 


9    t 


fe 


~  •  I  ^_i  ] 

PRESSURE  Ti*NK 
HEATER 


Typical  Methods  foi-  Heating  Water. 


ratus  is  eliminated  and  the  only  attention  necessary 
is  the  turning  on  and  ofif  of  the  current.  Some  of  the 
electric  devices  now  being  constructed  are  controlled 
automatically,  and  therefore  demand  no  attention 
whatever. 

Thermal  Characteristics  of  Water. — No  other 
known  liquid  or  solid  has  as  high  a  specific  heat  as 
water.  In  other  words,  water  has  a  greater  capacity 
for  storing  heat  energy  than  an  equal  weight  of  any 
liquid  or  solid  raised  an  equal  number  of  degrees  in 
temperature.      Its   capacity   for   storing   heat   may   be 


ELECTRIC     WATER     HEATING  95 

considered  analogous  to  that  of  a  sponge  for  absorb- 
ing water. 

After  the  boiling  point  of  water  is  reached,  steam 
begins  to  be  generated  and  unless  the  water  is  heated 
under  pressure,  it  no  longer  continues  to  store  energy, 
but  gives  off  the  heat  with  the  same  rapidity  it  is 
taken  up. 

Water,  like  other  liquids,  is  heated  by  convection 
currents  set  up  within  the  substance  itself.  Very  little 
of  the  heating  is  done  by  conduction  between  the  indi- 
vidual particles  of  which  it  is  composed.  The  con- 
vection currents  are  created  by  the  difference  in  weight 
of  hot  and  cold  water.  Whereas,  at  32°  F.  water 
weighs  62.42  pounds  per  cubic  foot,  it  only  weighs 
59.85  pounds  at  212°  F.  It  is  this  difference  in  weight 
that  causes  the  top  of  a  storage  tank  to  become  hot 
before  the  bottom,  and  which  creates  the  circulation 
in  the  ordinary  hot  water  heating  system. 


Cutler-Hammer  Instantaneous  Water  Heater. 

Electric   Energy  Required  for  Heating  Water — 

Assuming  the  weight  of  water  to  be  8.3356  pounds  per 
gallon  it  may  be  calculated  that  one  kilowatt  hour 
of  electric  energy  will  raise  409.33  gallons  of  water 
one  degree  F.  or  4.0933  gallons  100°  F.  If  a  water 
heater  of  one  kilowatt  capacity  be  operated  at  100 
per  cent  efficiency  it  would  accomplish  the  following 
results : 


96 


ELECTRIC     HEATING 


Raise     409.33    gal.        1°  F.    in      1    hour   and  consumo      1  kvv.-hr 

Raise  8.19    gal.      50°  F.    in      1    hour   and  consumo      1  kw -hr 

^'■^]^*^  „„    4.09    gal.    100°  F.    in      1    hour    and  con.sunie      1  kw.-hr 

Raise  9823.9     gal.        1°  F.   in   24   hours   and  consume   24  kw -hr 

Raiso     196.48   gal.      50°  F.   in   24   hours  and  consume   24  kw"-hr* 

Raise       98.24   gal.    100°  F.   in   24   hours   and  consume   24  kw!-hr! 

For  ordinary  calculations,  it  is  often  convenient 
to  remember  that  one  kilowatt  of  capacity  will  raise 
about  100  gallons  of  water  100°  F.  in  twenty-four 
hours. 


Westinghouse    Disc    Type 
Immersion  Heater. 


Simplex    Coil   Type    Immersion 
Heaters. 

Utilizing  Waste  Energy. — The  energy  utilized  in 
heating  water  is  expended  in  two  ways.  A  certain  per- 
centage is  required  to  supply  the  losses  of  heat  which 
take  place  on  account  of  radiation,  convection,  and 
conduction  from  the  heater,  piping  system,  and  stor- 
age tank.  Energy,  so  expended,  cannot  be  utilized  in 
any  other  way  and  is  entirely  wasted.  The  balance 
of  the  heat  energy  generated  may  be  called  the  useful 
energy,  as  it  alone  affords  the  user  his  supply  of  hot 
water.  It  is  therefore  apparent  that  every  possible 
effort  should  be  made  to  so  design  a  water  heating 
installation  that  the  losses  will  be  reduced  to  a  mini- 
mum, and  in  that  way  utilize  the  waste  energy.  This 
purpose  is  usually  accomplished  by  covering  the  pipes 
and  tank  with  material  of  low  heat  conductivity — a 
process  generally  known  as  lagging. 

Heat  Losses. — Authorities  vary  in  their  estimates 
of  heat  losses  from  metallic  surfaces,  between  1.5  and 
3  B.t.u.  per  square  foot  per  Fahrenheit  degree  differ- 


ELECTRIC     WATER     HEATING  97 

ence  in  temperature  per  hour.  The  loss  is  naturally 
greater  from  dark,  rough  radiator  surfaces  than  from 
the  brighter  and  smoother  ones  of  galvanized  iron 
tanks  and  pipes.  For  ordinary  water  heating  calcu- 
lations it  has  been  found  safe  to  figure  a  loss  of  0.6 
of  a  watt  (approximately  2  B.t.u.)  loss  per  square  foot 
per  Fahrenheit  degree  difference  of  temperature  per 
hour. 

The  tremendous  amount  of  heat  that  is  lost  from 
surfaces  of  exposed  water  tanks  and  piping  systems 
is  seldom  appreciated.  It  may  be  assumed,  for  in- 
stance, that  a  24  gallon  tank  of  water  having  an  ex- 
posed area  of  14  square  feet,  is  to  be  maintained  at 
a  temperature  of  100°  F.  above  that  of  the  surrounding 
atmosphere.  The  energy  that  would  be  required  to 
maintain  such  a  temperature,  provided  no  water  was 
drawn  off,  would  be  approximately : 

14X  .6X  100  =  840  watts. 

If  this  tank  were  heated  with  a  one  kilowatt  heater 
there  would  be  but  160  watts  of  the  total  capacity 
available  for  supplying  hot  water  at  the  required  tem- 
perature. In  this  instance,  the  energy  produced  by 
the  840  watts  of  the  heater  capacity  would  be  lost  and 
only  160  watts  capacity  utilized. 

Efficient  Lagging  Essential. — Had  this  tank  been 
covered  with  some  form  of  lagging  material  of  low 
heat  conductivity,  having  an  efficiency  of  say  85  per 
cent,  the  capacity  required  to  maintain  the  desired 
temperature  would  have  been : 

14  X  .6  XlOO  X  15%  =  126  watts. 

It  is  thus  apparent  that  the  energy  produced  by 
only  126  watts  capacity  could  be  lost,  whereas,  the  re- 
maining 874  watts  capacity  could  be  utilized  for  heat- 
ing water  to  the  required  temperature.  The  operating 
efficiency  of  the  unlagged  tank  installation  would  be 
16  per  cent,  whereas  it  would  be  87.4  per  cent  efficient 
when  lagged  in  the  manner  assumed. 

Table  1  indicates  the  number  of  gallons  of  water 
that  can  be  delivered  per  day  at  a  temperature  100°  F. 
above  that  of  the  water  supply  and  of  the   surround- 


98 


ELECTRIC     HEATING 


ing  atmosphere  with  various  installations.  The  figures 
are  based  on  the  use  of  seven  different  standard  sized 
tanks  and  six  different  capacity  heaters.  The  daily 
output  is  computed,  first  with  the  tanks  unlagged, 
second  with  a  50  per  cent  efficient  covering  applied, 
and  third  with  an  80  per  cent  efficient  covering  applied. 
Other  losses  than  those  from  the  surfaces  of  the  tanks 
are  not  considered. 


J.  M.  Magnesia  Sectional  Pipe  Covering. 


TABLE  1. 


Gallons  of  Water  per 

day — 

100°   F. 

Temperature  Rise. 

-.^^ 

Tank 

Dimensions    and 

Capacities. 

*  "1  J?    Gallons    Capacity . 

18 

24 

30 

40 

66 

82 

100 

^^       Dimensions... 

. . . . 

12"x3 

'  21"x4 

l'12"x5' 

14"x5' 

18"x5' 

20"x5' 

22"x5 

^O.S    Area  in  Sq.  F1 

.  .  . 

11 

14 

17.25 

21.3 

27 

30.5 

34 

Unlagged   .  . 

9 

750  Lagged  50% 

Eff.' 

42 

33 

23 

ii 

.  . 

Lagged  80% 

Eff. 

62 

58 

54 

49 

43 

38 

34 

Unlagged   .  . 

34 

16 

1000   Lagged  50% 

Eff'. 

67 

58 

48 

36 

i9 

'9 

Lagged  80% 

Efe. 

88 

83 

79 

74 

68 

63 

59 

Unlagged   .  . 

84 

66 

46 

22 

1500  Lagged  50% 

Efe'. 

117 

108 

98 

86 

69 

58 

48 

Lagged  80% 

Eff. 

137 

133 

129 

124 

118 

113 

109 

Unlagged   .  . 

116 

97 

72 

38 

17 

2000  Lagged  50% 

Efc'. 

158 

148 

136 

119 

109 

98 

Lagged  80% 

Eff. 

183 

179 

174 

168 

163 

159 

Unlagged    .  . 

197 

172 

138 

117 

96 

3000   Lagged  50% 

Eff. 

248 

236 

219 

209 

198 

Lagged  80% 

Eff. 

279 

274 

268 

263 

259 

Unlagged    .  . 

372 

338 

317 

296 

5000  Lagged  50% 

Eff'. 

436 

419 

408 

398 

Lagged  807c 

Eff. 

474 

468 

463 

459 

Methods  of  Heating  Water  Electrically. — There 
are  two  general  methods  of  heating  water  that  have 
come  into  general  use — the  instantaneous  method  and 


ELECTRIC     WATER     HEATING 


99 


the  thermal  storage  method.  The  former  makes  use 
of  special  devices  which  heat  the  water  as  it  passes 
from  the  faucet  and  which  are  not  connected  at  other 
times.    The  latter  method,  as  the  name  implies,  is  used 


\ 


United   Sales  Hot  Water  Faucet. 


100  ELECTRIC     HEATING 

for  heating  water  and  storing  it  for  future  use  in  a 
tank  or  reservoir. 

Two  types  of  heating  devices  are  commonly  used 
with  thermal  storage  systems — the  immersion  type, 
and  the  circulation  type.  The  former  is  usually  in- 
serted in  the  tank,  whereas  the  latter  is  connected 
with  pipes  outside  the  tank. 

Instaiitaneous  Water  Heating. — Devices  for  this 
class  of  service  are  usually  made  to  attach  to  the  ordi- 
nary water  faucet.  They  are  convenient  for  many  pur- 
poses where  only  small  quantities  of  hot  water  are 
needed.  As  it  is  possible  for  one  kilowatt  to  heat  only 
about  4  gallons  of  water  100°  F.  per  hour,  their  use  is 
naturally  somewhat  limited.  The  load  which  they 
create  is  often  considered  undesirable  on  account  of 
the  high  demand  and  relatively  low  energy  consump- 
tion. 

Instantaneous  heaters  are  usually  made  with  a 
resistance  coil  around  which  the  water  circulates,  and 
which  is  connected  when  the  faucet  is  opened.  Another 
device,  however,  consists  of  a  hollow  cylinder  and 
core  of  graphite.  When  the  water  flows  around  the 
core  inside  the  cylinder  it  acts  as  a  conductor  and  the 
flow  of  current  set  up  causes  heat  to  be  generated  in 
the  water  itself.  In  other  words,  the  water  is  heated 
in  the  same  way  as  in  the  common  water  rheostat. 

Thermal  Storage  Water  Heating. — The  thermal 
storage  method  is  more  often  employed  than  the  in- 
stantaneous method.  The  equipment  must  consist 
of  at  least  two  essential  parts — a  water  heater  and  a 
containing  vessel  for  storing  the  water  after  it  is 
heated.  With  an  equipment  of  this  kind  the  user  may 
store  up  a  large  quantity  of  hot  water  slowly  and  draw 
it  ofif  as  rapidly  as  he  wishes  when  it  becomes  heated. 
The  load  created  by  this  kind  of  a  heater  is  desirable 
on  account  of  its  low  demand  and  relatively  high 
energy  consumption.  It  is  apparent,  on  the  other 
hand,  that  such  equipments  are  necessarily  wasteful 
of  energy  unless  the  heat  stored  in  the  water  is  con- 
served. 


ELECTRIC     WATER     HEATING 


101 


Immersion  Type  Heaters. — The  heating  of  water 
or  other  liquids  is  accomplished  with  these  devices, 
by  the  insertion  of  resistance  elements  in  them.  Many 
types  of  immersion  heaters  have  been  developed.   Some 


Hatl^tti-rioi, 


roMOT  wAreit  ^Auetf 
MUST  BC  TA.KCNrifOM 

TOP  or  r 


eOL  o  wA  Ten 

HCJ 

Supply  p'ps 


Apfel    Immersion    Tank 
Heater. 


Coin  Circulation  Tank 
Heater. 


consist  of  open  coils  and  others  of  hermetically  sealed 
tubes.  Some  are  constructed  for  use  in  open  vessels, 
and  others  are  provided  with  fittings  for  attaching 
them  to  closed  tanks. 


102 


ELECTRIC     HEATING 


The  essential  advantage  of  this  type  of  heater, 
for  thermal  storage  water  heating,  is  that  the  device 
must  give  off  practically  all  its  heat  to  the  liquid.  En- 
ergy can  only  be  dissipated  indirectly  from  the  water 
and  surface  of  the  containing  vessel  or  directly  by  con- 
duction through  the  metallic  fiittings. 

Circulation  Type  Heaters. — It  is  customary, 
though  not  essential,  to  mount  a  circulation  type 
heater  outside  the  tank  or  reservoir.     A  pipe  leading 


Westinghouse     Circulation 
Heater. 


Westinghouse    Immersion 
Heater. 


from  the  bottom  of  the  containing  vessel  carries  the 
colder  water  to  the  heater.  As  the  water  becomes  hot- 
ter it  rises  through  another  pipe  connected  to  the  top 
of  the  containing  vessel.  This  process  continues,  re- 
gardless of  whether  any  pressure  is  applied,  until  all 
the  water  is  heated. 

Circulation  heaters  are  available  in  many  styles, 
forms,  and  sizes.  The  Westinghouse  heater  consists 
essentially  of  a  waterproof  bayonet  element,  inserted 
in  a  metal  casing,  and  designed  so  that  the  water  cir- 
culates around  the  heating  element  inside  the  casing. 
The  Simplex,  General  Electric,  and  many  other  types 
of  circulation  heaters,  are  made  up  of  resistance  wire 


ELECTRIC     WATER     HEATING  103 

wound  around  hollow  tubes  through  which  the  water 
passes.  The  Coin  Machine  heater  is  of  the  induction 
type,  and  so  designed  that  the  passage  of  current 
through  copper  wires  surrounding  an  iron  core  creates 
eddy  currents  in  the  iron  and  causes  it  to  heat.  The 
advantages  of  the  induction  type  heater  over  the  re- 
sistance types  are  its  rugged  construction  and  its 
capacity  for  running  dry  without  burning  out  when 
the  water  supply  is  cut  off.  The  present  designs  of 
induction  heaters,  however,  create  a  relatively  low 
power  factor  load,  averaging  about  80  per  cent. 

The  attractive  features  about  the  circulation  type 
heaters  are  the  ease  with  which  they  may  be  attached 
to  any  tank  or  containing  vessel,  and  the  facility  with 
which  they  may  be  removed  for  repairing  or  cleaning. 
The  water,  furthermore,  is  delivered  to  the  top  of  the 
tank  as  it  is  heated  and  is  soon  ready  for  use  even 
though  only  a  portion  of  the  tank  may  be  heated  when 
the  water  is  wanted.  The  great  disadvantage  is  the 
extra  radiating  surface  the  heaters  and  pipes  present, 
and  the  additional,  though  relatively  small,  heat  losses 
that  must  inevitably  result. 

Essential  Features  of  a  Water  Heater. — A  device 
of  this  character  should  be  durable,  easily  removed 
for  cleaning  or  repairing,  and  readily  controlled.  The 
surface  exposed  to  the  air  should  be  of  small  area 
or  thoroughly  insulated  from  heat  losses.  The  rela- 
tive area  of  the  heating  surface  exposed  to  the  water 
should  be  large  in  proportion  to  the  wattage  of  the 
heater.  Air  bubbles  and  deposits  will  inevitably  col- 
lect if  the  heating  element  is  operated  at  a  high  tem- 
perature. The  amount  of  scale  which  forms  inside 
the  heater  varies  widely  in  different  localities,  and  de- 
pends upon  the  amount  of  salts  in  solution.  The  scale 
may  be  chipped  off  or  removed  with  a  dilute  solution  of 
hydrochloric  acid.  In  either  the  instantaneous  or  circu- 
lation type  heaters,  it  is  generally  best  to  have  the 
water  passage  quite  large,  so  that  sediment  or  deposits 
will  not  obstruct  the  flow.  It  is  sometimes  desirable  to 
restrict  the  flow  of  water  through  a  circulation  heater 
in  order  that  it  may  rise  to  a  higher  temperature  as  it 


104 


ELECTRIC     HEATING 


passes.  This  may  be  done  by  making  the  passageway 
smaller  or  by  mounting  the  heater  somewhat  higher 
than  the  bottom  of  the  tank.  Water  heaters  that  cre- 
ate low  demands  and  are  required  for  long  hour  use 
are  generally  considered  more  desirable  load  builders 
than  those  constructed  for  high  demands  and  short 
hour  use. 

Automatic  Temperature  Control  Devices. — Where 
it  is  desirable  to  keep  a  supply  of  hot  water  available 
for  use  at  any  and  all  times  or  to  maintain  water  at  a 
certain  temperature  for  various  purposes,  automatic 
temperature  control  devices  have  a  wide  field  of  appli- 
cation. Electrical  apparatus  lends  itself  particularly 
well  to  automatic  control,  but  the  possibilities  it  natur- 
ally affords  are  as  yet  little  understood.  Any  device 
of  this  kind  that  will  cut  off  the  current  supply  imme- 
diately a  certain  predetermined  temperature  is  attained 
will  be  a  wonderful  convenience,  and  a  great  econ- 
omizer of  energy.  Its  general  application  cannot  but 
improve  the  diversity  factor  of  central  station  loads. 

Devices  of  this  character  should  be  simple,  durable, 
easily  repaired,  and  readily  adjusted. 


Performance    Curves    Therm    Elect     Water    Heater. 
Temperature   and   Load  Regulation,   24   hrs. 


ELECTRIC     WATER     HEATING  105 

Explanation    of   Temperatures    and    I^oad    Regulation    CurveH    of 
Tlierm-Eleet    lo(M)-watt    Water    Heater. 

The  above  curves  were  plotted  from  observations  taken  on 
the  24-hour  operation  of  a  1500-watt  tihermally-controlled 
Therm-Elect  Immersion  Heater  installed  in  a  standard  30-gal- 
lon  kitchen  boiler. 

The  heavy  black  lines  extending-  from  the  top  of  the  chart 
are  a  graphic  representation  of  the  hot  water  duty-cycle  im- 
posed upon  the  heating  system  in  a  liousehold  using  100  gallons 
of  116  degree   F.  water  per  day. 

The  length  of  each  line  is  in  proportion  to  tlie  gallons  of 
water  drawn  at  the  time  indicated  by  its  position;  covering  the 
day  from  the  preparation  of  breakfast  at  6:30  a.  m.  through 
the  bathing  period  from  9  to  10  p.  m. 

The  curve  in  the  center  of  the  chart  indicates  the  tempera- 
ture regulation  of  the  water  drawn  from  the  tank,  and  rep- 
resents a  regulation  of  95  per  cent  for  the  immersion  heater. 

The  load  curve  produced  by  the  six-point  thermal  control  is 
shown  at  the  bottom  of  the  page,  with  its  peaks  at  10  a.  m.,  3  p. 
m.  and  at  10  p.  m.,  and  its  valleys  at  6  a.  m.,  12  noon  and  6 
p.  m.,  indicating  the  diversity  which  would  be  obtained  with 
respect  to  a  cooking  load  operating  in  combination  wUh  the 
thermally-controlled   water-heater. 

Automatic  Time  Control  Devices. — Many  com- 
panies are  in  position  to  supply  energy  during  off  peak 
hours  at  lower  rates  than  during  the  period  of  maxi- 
mum load.  The  building  up  of  such  loads  by  means 
of  thermal  storage  water  heating  apparatus,  operated 
with  time  control  devices,  has  probably  not  been  given 
the  attention  heretofore  that  it  will  receive  in  the 
future.  The  loads  that  could  be  created  would  prove 
enormous. 

An  equipment  of  this  kind  naturally  requires 
larger  water  storage  facilities  than  one  that  may  be 
supplied  with  energy  at  any  and  all  times.  The  addi- 
tional storage  necessary  will  depend  on  the  number 
of  hours  during  which  the  energy  will  not  be  avail- 
able and  upon  the  quantity  and  temperature  of  the 
water  needed. 

Average  Hot  Water  Requirements. — Many  indi- 
viduals have  little  conception  of  the  amount  of  hot 
water  required  for  either  domestic  or  commercial  pur- 
poses. 

It  should  be  clearly  understood  that  when  30 
gallons  of  water  at  150°  F.  is  mixed  with  an  equal 
quantity  at  50°  F.  the  temperature  of  the  60  gallons 
will  be  100°  F.  The  temperature  of  bath  water  is 
usually  about  98°  F.,  whereas  120°  F.  is  scalding  tem- 
perature.    It  is  therefore  apparent  that  if  a  relatively 


106 


ELECTRIC     HEATING 


'Therm   Elect"    Immersion 
Heater  and   Thermostat. 


Hughes   Circulation   Heater 
Applied    to    Tank. 


ELECTRIC     WATER     HEATING 


107 


small  quantity  of  water  is  heated  to  a  high  tempera- 
ture, it  will  afford  a  considerably  larger  amount  when 
diluted  with  cold  water  for  ordinary  use.  The  hot 
water  requirements  of  hotels,  restaurants,  barber  shops, 


Good  Housekeeping-  Automatic  Temperature  Conti'ol 
Circulation   Watei-   Heater. 

and  other  commercial  users  is  generally  underes- 
timated, and  it  is  advisable  to  give  each  proposed  in- 
stallation careful  preliminary  consideration. 

Installation  of  Thermal  Storage  Water  Heaters. 

Correct  Plumbing  Essential. — The  relative  posi- 
tion of  the  tank  and  heater,  the  connections  between 
the  two,  the  size  of  tank  and  pipe  used,  the  elimina- 
tion of  air  pockets,  and  many  other  plumbing  features 
are  worthy  of  serious  consideration  when  a  thermal 
storage  water  heating  system  is  installed. 

The  tank  used  with  equipments  operated  under 
pressure  should  1)e  mounted  vertically  to  insure  maxi- 
mum difference  in  temperature  between  the  top  and 


108  ELECTRIC     HEATING 

bottom,  to  obviate  mixing  the  hot  and  cold  water  when 
the  supply  is  drawn  off  rapidly,  and  to  create  better 
circulation  of  water  through  the  heater.  Standard 
tanks  are  usually  fitted  with  two  taps  at  the  top. 
The  tap  used  for  connecting  the  tank  to  a  water  main 
should  be  provided  with  an  inside  pipe  connection  so 
that  the  cold  water  will  be  delivered  to  within  a  few 
inches  of  the  bottom.  It  is  necessary  to  have  a  very 
small  hole  drilled  in  this  vertical  pipe  near  the  top 
of  the  tank  to  prevent  the  water  being  drawn  out  by 
syphonage  whenever  a  hot  water  faucet  is  located 
below  the  level  of  the  tank  and  a  possibility  exists 
of  the  pressure  being  withdrawn.  Instances  of  where 
this  precaution  is  necessary  are  often  found  in  country 
residences  when  the  domestic  water  supply  is  furnished 
from  a  pressure  or  storage  tank.  It  is  obvious  that  if 
the  water  is  syphoned  out  of  the  water  tank  the  heater 
will  become  dry  and  possibly  burn  out. 

Installation  of  the  Heater. — Immersion  type  heat- 
ers are  usually,  though  not  necessarily,  inserted  in 
the  bottom  of  the  tank.  Circulation  type  heaters 
should  be  installed  as  close  to  the  storage  tank  as  pos- 
sible. Better  circulation  will  obtain  if  they  are 
mounted  vertically,  and  in  such  a  position  that  the 
lower  portion  of  the  heating  element  will  not  be  higher 
than  the  bottom  of  the  tank.  Rapid  circulation  is  not 
always  desirable,  however,  as  the  water  passing  through 
may  not  take  up  enough  heat  to  produce  the  desired 
difference  in  temperature  between  the  top  and  bottom 
of  the  tank. 

Pipe  Connections. — Circulation  type  heaters  should 
be  connected  with  pipe  unions  to  permit  of  their  quick 
and  easy  removal  for  inspection,  cleaning,  or  repairing. 
Unless  an  electric  heater  is  of  extremely  large  capacity 
in  proportion  to  the  size  of  the  storage  tank,  its  upper 
end  should  be  connected  either  to  the  hot  water  out- 
let or  to  a  special  tap  near  the  top  of  the  tank,  rather 
than  to  the  standard  side  outlet  usually  provided.  If 
the  hot  water  coming  from  the  heater  is  delivered  at 
or  near  the  top,  rather  than  at  the  side,  it  will  be  found 
that  the  circulation  will  be  better  and  that  a  quantity 


ELECTRIC     WATER     HEATING 


109 


of  hot  water  can  be  drawn  from  the  tank  much  more 
quickly  than  otherwise. 

By-Passing. — The  pipe  connections  at  the  top  of 
the  tank  should  be  carefully  arranged.  The  hot  water 
distribution  pipe  should  lead  straight  out  of  the  tank, 
and  the  connection  from  the  heater  should  connect  to 


Epco    Immersion    Heater    showing    Application    to 
Tank. 


it  from  the  side  as  close  to  the  tank  as  possible.  If  this 
precaution  is  not  taken  the  water  drawn  out  through 
the  distribution  pipes  may  come  partially  from  the  top 


110 


ELECTRIC     HEATING 


of  the  tank  and  partially  from  the  bottom  on  account 
of  the  rapid  suction  of  cold  water  through  the  heater. 
The  action  produced  is  somewhat  similar  to  that  in  an 
ordinary  atomizer  and  is  called  by-passing.  Some 
manufacturers  recommend  the  use  of  special  "non- 
by-pass  tees"  to  entirely  obviate  this  difficulty. 

Air  Pockets. — Unless  the  plumbing  is  properly 
done  and  the  hot  water  distribution  pipes  are  free  from 
air   pockets,   unsatisfactory   operation   is   likely   to   be 


Cutler-Hammer     Circulation     and     Immersion     Type 
Heaters    showing-    Form    of    Heating    Elements. 


charged  to  the  electric  heater.  Air  pockets  are 
formed  when  the  water  is  carried  up  and  finally  deliv- 
ered at  a  lower  point.  The  air  gradually  collects  at 
the  highest  point  and  prevents  the  passage  of  water. 
The  only  relief  from  such  a  condition  is  the  placing 
of  an  air  cock  at  the  highest  point,  or  a  rearrangement 
of  the  piping  system. 

Design  of  Distribution  System. — The  arrangement 
should  be  such  that  the  storage  tank  will  be  situated 


I 


I 


I 


ELECTRIC     WATER     HEATING  111 

as  near  as  possible  to  the  central  point  of  distribution. 
Connections  between  the  tank  and  faucets  should  be 
made  by  the  shortest  routes,  and  the  pipes  should  not 
be  larger  than  is  absolutely  necessary  for  satisfactory 
service.  The  longer  and  larger  the  pipes  that  are  used, 
the  greater  will  be  the  loss  through  radiation  from 
their  surfaces. 

So-called  ''return  systems,"  wherein  hot  water  is 
allowed  to  circulate  continuously  from  the  top  of  the 
tank,  through  the  distribution  pipes,  and  back  to  the 
bottom  of  the  tank,  will  be  found  to  require  much  more 
energy  for  their  operation  than  ordinary  systems,  on 
account  of  the  constant  heat  losses  that  take  place  from 
the  surface  of  the  pipes. 

Storage  Tank  and  Pipe  Lagging. — As  heretofore 
suggested  the  proper  lagging  of  tanks  and  piping  sys- 
tems is  often  of  as  much  importance  as  provision  for 
adequate  heater  capacity.  The  kind  of  material  em- 
ployed should  be  carefully  considered  and  the  most 
approved  methods  of  application  adopted.  Unless 
good  lagging  is  used  and  properly  applied,  the  oper- 
ating efficiencies  of  the  heating  system  may  be  greatly 
impaired.  A  few  of  the  commonly  known  types  of 
lagging  materials  are  described  and  the  methods  of 
application  outlined. 

Keystone  Tank  Cover. — This  form  of  lagging  con- 
sists of  a  %  in.  layer  of  compressed  hair  felt  having 
an  asbestos  lining,  and  a  canvas  cover.  Experiments 
show  that  this  form  of  lagging  will  prevent  at  least 
50  per  cent  of  the  usual  radiation  losses  from  the  sides 
of  an  exposed  tank. 

Keystone  covers  should  be  laced  tightly.  The 
upper  edge  of  the  cover  should  be  allowed  to  project 
at  least  half  an  inch  above  the  side  edges  of  the  tank. 
The  top  of  the  tank  should  then  be  covered  with  a  half- 
inch  layer  of  cement  and  pasted  over  with  six-ounce 
drill. 

Economy  Tank  Covers. — The  Johns-Manville 
Economy  tank  covers  are  made  up  olf  1  in.  hair  felt  lined 
with  asbestos  and  covered  with  a  canvas  jacket.  They 
are  designed  to  hit  the  standard  water  tanks.    The  top 


112 


ELECTRIC     HEATING 


and  sides  are  in  one  piece  and  may  be  laced  tightly 
around  the  tank.  A  rope  wrapped  temporarily  about 
the  jacket  will  hold  it  in  place  and  make  the  lacing 
much  easier. 

When  the  tank  is  exposed  the  canvas  jacket 
should  have  a  coat  of  sizing  and  be  painted  with  two 
coats  of  cold  water  paint  or  lead  and  oil. 


or  WATER    SERVICE   Pipe 


TOP  conNEcrioH 

eilTHCR  TOSERVIce. 
flPZ    on   Tt^HK 


simplex   Heater  and  Stand- 
ard  Pipe   Connections. 


Economy    Covering   Applied 
to   Tank   and   Pipes. 


The  manufacturers  claim  an  efficiency  for  this 
form  of  lagging  of  from  85  per  cent  to  90  per  cent. 
Although  Economy  covers  cost  about  twice  as  much  as 
Keystone  covers  the  increased  savings  which  they 
effect  warrant  their  use. 


ELECTRIC     WATER     HEATING  113 

Directions  for  Lacing  Tank  Covers. — Start  lacing 
at  the  top  of  the  cover.  Tie  the  end  of  the  lace  to 
the  right  hand  eyelet  and  thread  it  over  to  the  oppo- 
site eyelet.  Make  two  loops  and  then  lace  diagonally 
under  the  cover  to  the  eyelet  below  the  first  and  make 
two  loops.  Repeat  the  process  until  the  last  pair  of 
eyelets  is  reached  and  then  make  three  loops.  Lace 
one  of  these  loops  back  and  tie  it  to  the  lace  end  by 
means  of  a  bowknot  beneath  the  cover. 

Block  Lagging. — Many  forms  of  heat  insulating 
blocks  for  lagging  the  larger  sized  tanks  are  available. 
One  inch  thickness  is  usually  recommended  for  water 
tanks  and  the  insulating  efficiencies  may  be  figured 
at  from  80  per  c,ent  to  90  per  cent  depending  upon  the 
material  used  and  the  care  with  which  it  is  applied. 
The  blocks  usually  come  in  strips  about  6  in.  wide  and 
3  ft.  long. 

For  lagging  the  sides  of  a  small  tank  the  blocks 
are  usually  cut  in  strips  about  3  in.  in  width  so  that 
they  will  more  nearly  conform  with  the  surface  con- 
tour. These  strips  are  then  placed  around  and  length- 
wise of  the  tank  and  held  in  position  temporarily  with 
a  small  rope.  The  blocks  are  allowed  to  project  about 
1^  in.  over  each  end  of  the  tank  to  conform  with  the 
top  and  bottom  lagging.  Soft  annealed  wire  (about 
No.  16  gauge)  is  then  wound  around  the  blocks  and 
tightened  up  so  as  to  hold  them  firmly  in  place.  The 
blocks  are  then  beaten  down  into  shape  with  a  wood 
paddle  or  mallet  so  that  no  air  passages  may  be  left 
between  the  covering  and  the  tank. 

Cement  is  then  mixed  with  water  to  about  the  con- 
sistency of  ordinary  mortar  and  applied  to  the  outside 
about  y2  in.  in  thickness  by  means  of  a  trowel.  All 
cracks  and  crevices  should  be  filled,  and  the  surface 
made  smooth  and  even.  A  six-ounce  drill  jacket  is 
then  pasted  on  the  outside.  Flour  and  water  may  be 
used  for  paste.  The  salvage  edges  of  the  drill  should 
be  torn  off,  before  it  is  dipped  in  the  paste,  to  prevent 
puckering. 

The  ends  of  the  tank  ar^  usually  lagged  with  small 
blocks  wired  in  position     (when    possible),    pounded 


114  ELECTRIC     HEATING 

down,  coated  with  cement  and  a  drill  cover  pasted  on 
in  a  similar  way  to  that  suggested  for  the  sides.  When 
the  tank  is  convex  at  the  bottom  or  so  mounted  that 
the  blocks  cannot  be  placed  in  position,  a  coating  of 
soft  cement  is  put  on  the  surface  of  the  tank  first.  The 
blocks  will  then  adhere  to  the  outside  while  the  next 
coating  of  cement  is  trowelled  over  them  and  the 
covering  is  put  in  place. 

Pipe  Lagging. — A  large  variety  of  coverings  are 
available  for  lagging  pipes  and  fittings.  Sectional  pipe 
covering  which  may  be  hinged  over,  pasted  together 
by  means  of  a  lap  in  the  canvas  jacket,  and  held  secure 
with  brass  bands,  is  most  commonly  used.  It  may  be 
secured  in  thicknesses  varying  from  ^  to  3  inches,  but 
for  water  piping,  1  in.  thickness  is  ample.  It  is  usually 
made  up  in  3  ft.  lengths.  The  savings  in  heat  that 
may  be  effected  by  the  careful  lagging  of  pipes  and  fit- 
tings are  enormous.  Fifty  feet  of  1  in.  pipe  for  in- 
stance, has  approximately  the  same  area  as  a  thirty 
gallon  tank,  and  filled  with  water  at  the  same  temper- 
ture,  will  radiate  heat  just  as  rapidly. 

It  is  of  the  utmost  importance  that  the  pipe  leading 
from  the  heater  to  the  top  of  the  tank  should  be  lagged 
when  water  is  heated  by  the  circulation  method.  The 
water  circulates  constantly  in  this  portion  of  the  sys- 
tem as  long  as  the  heater  is  in  service. 


J.   M.    Asbestocel   Sectional    Pipe   Covering". 


CHAPTER  VIII 

ELECTRIC  HEATING  OF  BUILDINGS. 

Use  and  Advantages. — Were  it  possible  to  heat 
buildings  with  electricity  at  no  greater  cost  than  with 
combustion  methods,  it  would  be  only  a  matter  of  time 
until  they  would  all  be  heated  electrically  on  account 
of  the  many  superior  advantages  aflforded.  The  pres- 
ent high  cost  of  generating  and  distributing  electric 
energy,  however,  precludes  its  universal  application 
as  a  substitute  for  fuel  heat.  It  is  only  in  localities 
where  fuel  is  very  costly,  or  where  electricity  may  be 
used  for  heating  during  off-peak  seasons  or  oflf-peak 
hours,  that  extensive  use  may  be   made  of  it  as   an 


Westinghouse    Convection    Heater. 

air  heating  medium.  In  some  sections  of  the  west, 
where  water  power  is  used  extensively  for  irrigation 
pumping  in  the  summer,  it  has  been  applied  during 
the  winter  season  to  the  heating  of  buildings  with  con- 
siderable success.  The  energy  so  used,  which  might 
otherwise  be  wasted,  is  turned  into  a  useful  by-product 
and  sold  at  a  low  rate  in  competition  with  coal  and 
other  fuels,  at  the  same  time  netting  the  central  sta- 
tions a  small  profit. 


116 


ELECTRIC     HEATING 


Some  attention  has  also  been  given  to  the  devel- 
opment of  electric  heating  systems  designed  to  make 
use  of  the  great  heat  storage  capacity  of  water,  and  so 
arranged  as  to  heat  large  quantities  of  it  during  off- 
peak  hours  for  use  in  warming  buildings.  Where  con- 
ditions are  favorable  this  method  should  find  a  wide 
application. 

In  a  general  way  it  may  be  stated  that  electric 
energy  is  too  costly  to  compete  with  ordinary  fuels,  but 
where  the  cost  of  heating  a  building  is  a  relatively 
unimportant  item  in  comparison   with   the  desire   for 


General    Electric 
Convection    Heater. 


Majestic   Radiant   Heater. 

convenience,  it  is  certain  to  meet  with  favor.  For 
heating  small  offices,  bath  rooms,  sick  rooms,  cold  cor- 
ners, and  for  taking  the  chill  out  of  the  air  during  mild 
weather  its  use  is  ideal. 

Electricity  has  the  peculiar  advantage  of  being 
instantly  available,  and  regulated  at  will.  It  neither 
destroys  oxygen  nor  vitiates  the  atmosphere.  It  is  the 
cleanest  and  safest  known  method  of  heating.  Among 
the  advantages  of  electric  heaters,  are  ease  of  instal- 
lation, simplicity  of  operation,  portability,  flexibility 
of  location,  and  small  floor  space  required. 

There  are  certain  customers  in  nearly  every 
locality  that  are  willing  to  pay  for  the  luxury  afforded 
by  electric  heat,  regardless  of  its  cost,  provided  its  ad- 


ELECTRIC     HEATING     OF     BUILDINGS 


117 


vantages  are  made  known  to  them.  These  individuals, 
in  most  instances,  may  be  readily  singled  out  and  de- 
sirable business  secured  with  little  effort. 

Comparative  Cost  of  Fuel  and  Electric  Heat. — It 
should  be  understood  that  electric  air  radiators  always 
operate  at  100  per  cent  efficiency,  whereas  coal  and 
gas  apparatus  may  often  operate  at  efficiencies  as  low 
as  10  per  cent.  By  referring  to  the  comparison  of  costs 
of  fuel  and  electric  heat  set  forth  in  Chapter  I,  it  will 
be  noted  that  600  B.t.u.  gas  at  $1.00  per  thousand  cubic 
feet  operating  at  20  per  cent  efficiency  is  about  equiv- 
alent to  electricity  at  3  cents  per  kilowatt  hour. 


Hughes  Convection  Heater. 


Electric  Heating  Systems. — A  large  variety  of  sys- 
tems of  electric  heating  are  in  use,  but  few  data  are 
available  to  show  their  relative  efficiencies  and  merits. 
On  the  assumption  that  the  application  of  electricity 
to  the  heating  of  air  is  100  per  cent  efficient,  it  is 
obvious  that  the  essential  feature  to  be  considered  with 
each  system  is  the  proper  distribution  of  the  heated 


118 


ELECTRIC     HEATING 


air.  If  the  heat  is  intense  near  the  heater  or  radiator 
and  other  parts'  of  the  room  are  cold  the  results  will 
not  be  satisfactory.  It  is  essential,  therefore,  that  the 
system  employed  should  not  only  heat  the  air  but 
should  set  up  convection  currents  that  will  serve  to 
distribute  it.  The  size,  type,  operating  temperature,  and 
design  of  the  heaters  have  much  to  do  with  this  par- 
ticular feature. 

The  commonly  known  methods  of  electric  heating 
are  (1)  by  radiant  heaters,  (2)  by  convection  heaters, 
(3)  by  oil  and  water  radiators,  (4)  by  indirect  air  heat- 
ing systems,  and  (5)  by  steam  and  hot  water  circula- 
tion systems. 

Radiant  Heaters. — Radiant  or  Idilminous  type  heat- 
ers are  made  in  a  variety  of  styles  and  sizes.  The  heat- 


Estate  Convection  Heater. 


ELECTRIC     HEATING     OF     BUILDINGS  119 

ing  elements  may  consist  of  coils  of  exposed  wire  or 
filaments  within  glass  globes,  which  are  heated  to  a 
glowing  temperature.  The  units  are  usually  mounted 
in  front  of  polished  reflectors  which  focus  the  heat  in 
any  desired  direction.     Some  radiant  heaters  are  man- 


Westinghouse   Flush   Type   Radiant  Heater. 

ufactured  in  small  portable  sizes,  whereas  others  are 
made  for  use  in  open  fireplaces  or  for  flush  wall 
mounting. 

The  heat  from  glower  type  radiators  is  like  sun- 
shine in  that  it  only  raises  the  temperature  of  a  body 
which  is  opaque  to  heat  waves.  It  passes  through  the 
air  without  heating  it  perceptibly,  and  only  causes 
a  rise  of  temperature  in  the  air  by  heating  objects  that 
offer  opposition  to  its  passage,  these  objects  in  turn 
heating  the  air  in  contact  with  them  by  conduction. 

Heat  waves  are  unaffected  by  air  currents  and 
glower  type  radiators  are  therefore  convenient  for 
warming  portions  of  the  body  or  for  warming  a  person 
in  a  large  open  space.    The  light,  cosy  glow  which  they 


120 


ELECTRIC     HEATING 


emit  makes  these  heaters  very  attractive  and  cheerful 
in  the  home  or  office. 

It  is  often  thought  that  a  glow  type  radiator,  in 
front  of  which  it  is  uncomfortable  to  hold  one's  hands, 
must  be  emitting  more  heat  than  a  resistance  type, 
over  which  they  may  be  held  for  any  length  of  time 


\miii 


r^Jf 


€^ 


^ 


nsa^ 


'"-^^ 


Hot  Point  Radiant  Heater. 


without  any  sense  of  discomfort.  This  impression  is 
wrong,  because  all  the  energy  delivered  to  any  elec- 
tric heater,  regardless  of  the  type,  is  transformed  into 
heat  energy.  The  glower  type  heater  concentrates 
the  heat  by  means  of  polished  reflectors,  while  the 
resistor  type  distributes  the  heat  through  the  air.  Uni- 
form temperature  throughout  a  room  cannot  readily 
be  attained  with  a  glower  type  heater. 

Convection  Heaters. — Heaters  of  this  type  are  also 
manufactured  in  a  variety  of  sizes  and  capacities.  They 
usually  consist  of  coils  of  resistance  wires  or  ribbons 
mounted  on  ornamental  frames,  surrounded  with  a 
sheet  metal  or  cast  iron  casing,  with  openings  above 
and  below  to  permit  the  free  passage  of  air  through  the 
coils.  The  elements  are  generally  designed  for  opera- 
tion at  temperatures  below  the  red  heat.  The  warmth 
generated  by  this  type  of  heater  is  transferred  to  the 
air  bv  direct  contact  with  the  hot  resistance  elements 


ELECTRIC     HEATING     OF     BUILDINGS  121 

and  the  surface  of  the  heater.  Convection  currents  are 
consequently  set  up  which  tend  to  equalize  the  room 
temperature.  Much  depends  upon  the  design  of  this 
type  of  heater,  if  proper  heat  distribution  is  to  be 
attained.  The  construction  should  be  such  as  to 
develop  ample  circulation  of  air  through  the  heated 
coils. 

Convection  heaters  should  never  be  mounted  flush 
with  the  walls.  They  should  be  set  a  short  distance 
away  from  the  sides  of  a  room.  Where  this  is  im- 
possible, guards  should  be  mounted  on  top  of  the  heat- 
ers to  deflect  the  heated  air  toward  the  center  of  the 


Simplex   Convection    Heater. 

room.  The  tops  of  the  heaters  should  be  unobstructed 
in  order  to  permit  free  passage  of  air.  Two  or  more 
small  heaters  will  always  be  found  to  give  a  better  dis- 
tribution of  heat  than  a  single  large  one.  Heaters 
placed  under  windows  will  warm  the  air  admitted  to 
a  room  and  tend  to  obviate  unpleasant  draughts.  Con- 
vection heaters  in  capacities  larger  than  750  watts  are 
usually  provided  with  three-heat  switches  to  permit 
operation  at  lower  temperatures  during  mild  weather. 
Oil  and  Water  Radiators. — A  large  number  of  oil 
and  water  radiators  have  been  placed  upon  the  market. 
They  are  usually  made  in  the  form  of  ordinary  hot 
water  radiators  with  the  heating  elements  inserted  in 


122 


ELECTRIC     HEATING 


the  sides  and  immersed  in  liquids.  Their  chief  advan- 
tage IS  in  the  greater  radiating  surface  which  they  offer 
to  the  air  in  comparison  with  ordinary  convection  air 
heaters.  The  heating  elements  being  submerged  in  the 
liquid  operate  at  low  temperatures  and  are  less  subject 


Hot  Point  Convection  Heater. 


to  oxidation.  The  water  or  oil  which  is  used  holds  the 
heat  for  a  considerable  time  after  the  current  is  shut 
off.  The  oil  radiators  may  be  operated  at  a  higher 
temperature  than  the  water  radiators  because  oil  vapor- 
izes at  higher  temperatures.  The  disadvantages  of  this 
type  of  heater  are  the  slowness  with  which  it  heats  up, 
its  greater  weight  and  lack  of  portability,  and  its  higher 
manufacturing  cost,  in  comparison  with  convection 
heaters. 

Indirect  Air  Heaters. — Radiators  which  are  used  to 
heat  the  air  in  a  passage  or  flue  which  supplies  air  to  a 
room  are  called  indirect  heaters.  The  radiators  may 
consist  of  coils  of  wire  or  cast  grid  resistance  mounted 
on  a  frame  work  so  as  to  allow  free  passage  of  air  and 
placed  in  a  chamber  or  box  at  the  foot  of  vertical 
flues  leading  to  the  rooms  to  be  heated.  Air  is  ad- 
mitted to  the  chamber  from  the  outside,  and  after 
passing  through  the  heated  resistance,  it  is  taken 
directly  into  the  flue.  Ventilating  fans  may  be  inter- 
posed between  the  heating  chamber  and  the  outside 
in  order  to  increase  the  volume  of  air. 

Installations  of  this  character  in  individual 
capacities  of  several  hundred  kilowatts  have  been  in 


ELECTRIC     HEATING     OF     BUILDINGS 


123 


successful  service  for  a  number  of  years.  The  chief 
advantages  have  been  found  to  be  a  marked  saving 
in  floor  space,  ease  of  operation,  cleanliness,  and  lack 
of  attention  required. 

Steam  and  Hot  Water  Systems. — Electrically 
heated  steam  and  hot  water  systems  are  similar  in 
every  respect  to  ordinary  fuel  burning  equipment, 
except  that  electric  steam  boilers  and  water  heaters 
are  substituted.  A  number  of  installations  have  been 
made  which  have  proved  very  satisfactory.  The 
chief  advantages  are  even  heat  distribution,  ease  of 
operation,    freedom    from    dirt,    soot,    and    ashes,    and 


Apfel   Water   Radiator. 


less  attention  required.  It  is  apparent,  however,  that 
unless  buildings  are  already  equipped  with  steam  or 
hot  water  heating  systems,  the  cost  of  installation  will 
be  considerable  greater  than  for  direct  air  heating 
systems. 

Installation  of  Electric  Heaters. — The  use  of  nu- 
merous small  heaters  of  three  kilowatts  capacity  or 
less,  each  provided  with  three-heat  switches,  creates 
a  better  diversity  of  load  for  the  central  station  than 
a  few  large  single  heat  heaters. 

Many  concerns  require  that  buildings  wired  for 
electric  heating  shall  be  provided  with  220  volt  serv- 
ice in  order  to  prevent  the  use  of  lights  and  lamp 
socket  devices  on  special  heating  circuits.     Such  pro- 


124 


ELECTRIC     HEATING 


vision  has  the  further  advantages  of  reducing  the  costs 
of  wiring  and  service  connections  and  producing  better 
balanced  load  conditions. 

In  making  installations  of  electric  heaters  of  all 
types  every  facility  should  be  provided  for  convenient 
operation,  otherwise  the  habit  of  opening  windows, 
rather  than  turning  off  the  current  when  the  room  be- 
comes too  warm,  will  be  encouraged. 

Calculation  of  Heat  Requirements. — The  energy 
needed  to  heat  a  building  or  an  individual  room  is  the 
sum  of  the  heat  required  to  warm  the  air  for  proper 


Radiator  with   Coin   Circulation   Water 
Heater   Attaclied. 

ventilation  and  that  which  is  transmitted  to  the  out- 
side and  lost.  The  former  varies  with  the  use  for 
which  the  building  is  required,  and  the  latter  with 
the  nature  of  its  construction,  exposure,  etc.  They 
both  vary  with  the  difference  in  temperature  between 
the  outside  and  inside  of  the  buildings. 

The  two  most  commonly  known  ways  of  calcu- 
lating the  heat  requirements  of  a  building  are  (1)  by 


ELECTRIC     HEATING     OF     BUILDINGS  125 

the  use  of  the  "B.t.u.  method"  and  (2)  by  the  appli- 
cation of  an  empirical  formula.  We  shall  call  the 
B.t.u.  method,  the  "watt  method"  because,  for  con- 
venience, all  calculations  will  be  made  with  watts 
rather  than  with  British  thermal  units.  The  watt 
method  is  naturally  more  accurate,  whereas  the  em- 
pirical formula  is  easier  handled.  The  empirical  form- 
ula is  based  on  the  watt  method  but  is  more  general 
in  its  application.  It  is  convenient  for  making  prelim- 
inary estimates. 

Watt  Method. — Calculation  based  on  this  method 
take  into  account  the  heat  in  watts  (1)  to  heat  the  air 
required  for  ventilation  as  well  as  the  air  which  leaks 
around  windows,  doors,  and  various  crevices ;  (2)  to 
supply  the  losses  by  transmission  of  heat  to  the  out- 
side through  the  walls,  window^s,  floors,  and  ceilings. 
The  sum  of  the  watts  required  by  a  building  for  heat- 
ing the  air  and  for  supplying  the  losses  will  determine 
the  heater  capacities. 

Heat  Absorbed  by  Air. — One  cubic  foot  of  air  will 
absorb  approximately  0.0054  watts  per  hour  per  degree 
Fahrenheit  diflference  in  temperature.  In  order  to 
determine  the  amount  of  heat  required  for  heating  the 
atmosphere  inside  a  building,  it  is  necessary  to  multiply 
the  number  of  cubic  feet  of  air  per  hour  admitted  to 
the  building  by  the  difiference  between  the  outside 
temperature  and  that  required  within,  and  by  the 
constant  0.0054. 

i.e.,  quantity  of  air  X  temperature  difference  X  0.0054 
=  watts  per  hour. 

The  quantity  of  air  admitted  to  a  building  de- 
pends upon  (1)  the  ventilation  required,  and  (2)  the 
air  leakage.  Ventilation  requirements  may  be  fixed 
by  law  for  some  classes  of  buildings  and  for  others 
the  amount  is  usually  fixed  by  the  architects'  judg- 
ment. The  character  and  habits  of  the  people  living 
in  a  building  also  have  much  to  do  with  its  ventila- 
tion. The  following  table  gives  a  fair  average  of  the 
amount  of  air  that  is  usually  required  for  various  kinds 
of  buildings : 


i2§  WUDCme    HKAIiNO 

Atnt^mmj^  Hn>i\n, ,.,,.,.,,,,, ,,  %tfm  m,  ft,  pt^r  nf^i, 
Vki4ftvri*ftt  ttm  workuptvn, ,  I .,  i»fi|(»  ««,  ti,  vt*r  pfrmoft, 

(hf  lAviim  rttftmn,,  <*vo  n>ii,\,\:  ,    «  x/t^r  hour 

(a)  MftJJw    (¥if\iU    ttpt»u    «ffl>rw«vc/     thrtx?    itfUtp^^m 
t'hutiitfp*  pt't'  fitmr. 

H««t  Lo«t  by  Tftniml»»iofi.— The  ♦^  tn-  1,--  t,r«r 
irjwftf©  /r^t  of  iUffftce  per  Fttlif^tilidt  dcK"  '  i"'  '  > ' ' 
hi  ti^wpeffttiffe^  between  <he  ifi^i^le  atid  otit^irlr  <>\  hnjld- 
ifigM  a»nl  roonii,  a>»  >»et  fr^fth  in  the  »foll(>wing  tabic, 
»€effli  to  b«  pretty  well  ei^tabliwhed  by  the  beit  an 
th(/fitieM; 

4--iU(ih  hrU'H  Wttll, ,,,,,,,,.,» t .,,,,,,,.,  i  ^>iU  Wtttt* 

if--iff^h  itrU'U  wt*i], ,,,,,,  1 1 II I  mm,  til,,  O.iH  wnitn 

ii-'iw'U  init'H  w»^i, ,11, ,,,,,,,,, ,,,,,t,ti  #/#||  WAii« 

^di  i»»/i,  htittk  whli, .,,,,,,,,,,,,,,,,,,,,,  0Mfi  WttHM 

'  1  iUifuff^iii  wt^Uti,,,,,,,,,,,,,,,  i,i  n  hi'>'  ■'•♦« 

//ftJJw    ,,/,;,///,,,/,/!#//,*////»    1.6  *   bfh  ■  milt 

»>oH*  Hin**n  ,,,,,,,,,,,,,,,,,,,,,,,,,,  0,100  wnffw 

l-'i/K'h  woort  i»ttf(H|ott   ,///,// #11 //,/*«/»  O.iaio  wititi* 

WuhfSttu  HmmfiM  (aotih\t§  h^^mi,,,,,,,,,  9M  wtttm 

ti'\tt*prou(   rtof/f'fn^, ,,,,,,,,,,,,,,,,,,,,,,  0,080  Wfltt« 


r>JM  tinnthm, ,.,..,,  t,  ,,,>,,,,,,,>,  ill, ,  9,999 
Witiifimt  ('f\uiipS' ,,  i ,,,,,,  1 1 ,,,,  i ,  t ,,,.,, ,  0,051 
H«w»^r»«f|  #<^inH«f  (fiff  pfmr  ft|»«v») ,,,,,, ,  Mf4 

Wo/'fl*-**  «'*«ll)«Mw  tmrief  Ifon  ro§t,,,,,,,,  0,060  w«tt« 

irhfpi'itur  ('niiffiffn  ,,.,,,,,,,,,,,,,,,,,,,  0,04*  wtttfx 

Wo<>f1uH  rtoof  :,.,,,,,,,,,,,,,,,,,,,,,,,,  0,1|0  WttttM 

poo»'  {«/»  whun,  J/»  inftM,,,,,,,,,, /,,,«,  0,170  wflttN 

plf««l**   wifinow   «|tt»B, ,,,,,,,,,,,,,,,,/!,  O;»00  w«(t« 

hoHf>l«i  wlfjflow  ^)»«i,,,,, /,,,,,,,,,«,,,,  0,170  WrtttN 

HIh«I«<  ««k>')lMht , ,  / , ,  ( r  I  >  f  I  f  I ,  > , ,  I , , ,  <  /  /  /  /  0/96^  WKtiM 

/»<*HlH*i  nky\\^tM,,,,,,,,,,,,,,,,,,,,,, ,, ,  0,1»6  wflii* 

To  obttthi  th«  Witti  loMt  by  int»iHiiiJf4^ir>fi,  multiply 
the  Hft?tt«  of  the  respeetlve  surfflceft,  by  the  tctiipera- 
ture  (llfferenee  between  the  exterior  and  the  ititerior 
of  the  bulldlnii  or  roofn,  and  by  the  wattafi^e  eon«tant» 
In  the  above  table. 

I.e.,  area  X  temperature  diflference  X  ceoitant 
*«watt»  tfanwmjtted. 

Air  Ltikift.-=^A  careftil  cofi>»ideration  of  air  leak- 
age l»  of  ai  mvieh  Importance  In  the  de»i|(n  of  heating 
Initallations  a»  1m  that  of  ventilation,  The  lo§»eg  of 
heat  on  at'eonnt  of  air  leakage  eannot  be  ealenlated 
readily,  and  are  nMually  estimated.    Air  leakage  dimply 


\\\  AuuMu\u  vATvwvis  wi\h  rtiw  ^iit*.    Willi  |«t^> 

j\^Ae<siu  tH\,  w^^wifif  wv^rt  h^t  th^«  t^>^  mM  h^vU^ 

wiM  \NU\^h  s\a\  \\\a\\  on  n  ^ 

ov   \v>on\,  aopon*!  lo  a  ^ft^XtV  tWtWX  \\]M\\\  \\\t  AX\^  oi 
«^\|Hv^cvl  \V;%U?i  UUW  WJHVW  M\>i'  \Mh<^r  (t^u\r«  *\t  ih<?  v^V 

hv  \\\k{  X\\t  \\tii\0\tf'^  )\M\!^\\\t\\X  \\\\\n^  \'  ■    ■ 

\-                                                        ,  «  «    V^Wt  Vo  ^H 

w  Uv\V|j[ 


128  ELECTRIC     HEATING 

Empirical  Formula. — A  vast  number  of  empirical 
formulae  have  been  developed  for  rapid  calculation  of 
the  heating  of  buildings,  but  it  is  thought  that  the 
following  formula  will  come  closer  to  meeting  the 
average  requirements  than  most  of  those  in  use : 

(l80    ~^^^^"^^^   J  (T1  —  T2)  ^  Watts  capacity. 

N  =:=  number  of  chang-es  of  air  per  liour. 

Cz=:  cubical  contents  of  building. 
K=r  constant   depending  upon   exposure   and   intermittent   cliar- 

acter    of    heating. 
Wz=  square   feet  of  exposed   wall   surface. 

Gzir  square  feet  of  exposed  glass  surface. 
Tj  =  inside  temperature  in  Fahrenlieit  degrees. 
T2=:  Outside  temperature   in   Fahrenheit  degrees. 
Values  of  N: 

cubic  feet  of  air  required  per  hour  for  ventilation. 


N 


Cubic  contents  of  building. 
N  =r  1  for  residence  sleeping  rooms. 
N  z=  2   for   residence   living   rooms. 
]V  =  3   for  residence  halls   (with  open  stairways.) 
Values  of  K: 

K  =  1  where  walls  are  not  exposed  to  prevailing  winds. 
Kizrl.l  to  1.5  wliere  walls  are  exposed  to  prevailing  winds. 
K=rl.l    to   1.25   where   walls   are   not   exposed    to   prevailing 

winds  and  building  is  heated  only  during  the  day. 
K  =  1.2  to  1.75  where  walls  are  exposed  to  prevailing  winds 

and  building  is  heated   only  during  the   day. 
K  3=1.25   to  2  where  building  is  heated  intermittently  with 

long   intervals   of   non-heating. 

This  formula  may  be  applied  to  any  well  con- 
structed frame  or  brick  building.  Due  allowance 
should  be  made  for  poorly  constructed  buildings.  For 
use  in  any  particular  locality,  the  above  formula  may 
be  modified  to  suit  local  conditions  of  temperature  and 
types  of  building  construction. 

Application  of  Methods. — The  following  example 
is  worked  out  by  both  the  watt  method  and  the  em- 
pirical formula  to  show  the  application  of  the  two 
methods  of  calculating  heater  capacities : 

Assume  15  by  12  by  8  foot  corner  living  room  of 
a  residence  facing  prevailing  winds  on  two  sides.  The 
room  has  8-inch  outer  brick  walls,  two  single  glass 
windows  each  having  an  area  of  15  square  feet,  and  an 


ELECTRIC     HEATING     OF     BUILDINGS  129 

outer  wooden  door  having  an  area  of  21  square  feet. 
The  temperature  of  the  room  is  to  be  maintained  at  70 
degrees  F.,  when  the  lowest  outside  temperature  is 
zero  degrees  F.  Other  rooms  in  the  house  are  to  be 
heated  to  a  similar  temperature,  and  the  losses  through 
the  partitions,  floors  and  ceilings  are  therefore 
neglected. 

Watt  Method:  Watts. 

Air     1440  cu.  ft.  X  2  X  •0054X  70^  1088 

i^xposed    waUs 165  sq.  ft.  X -135  X  70  ==  1560  +  20%  =:  1872 

Exposed    windows.      30  sq.  ft.  X  -300  X  70  r=:    630 -j- 20%  r=    756 
Exposed    door 21  sq.  ft.  X  -120  X  70  =    175 -f  20%  :=    210 

Total    3926 

Empirical  formula  method : 

Substituting  values  in  formula  on  p,  128: 

(^^^ +1.2(1^^ +f))(70°-0= 

=  Watts  capacity. 

[16  +  1.2  (23.25  +  10)  ]  70=  watts   capacity. 
(16  +  39.9)  70  =  3913  watts  capacity. 

In  order  to  properly  heat  the  room  a  2000  watt 
three-heat  radiator  should  be  installed  under  each 
window. 


CHAPTEE  IX 

INDUSTRIAL  HEATING. 

Scope  of  Application. — The  field  for  the  introduc- 
tion of  electric  heat  for  industrial  purposes  covers  a 
great  variety  of  applications  in  which  direct  combus- 
tion methods  and  steam  heat  are  now  used.  The  pres- 
ent status  of  development  is  in  a  way  comparable  to 
that  of  the  electric  motor  about  a  decade  ago.  The 
adoption  of  electric  heat  presents  the  same  advantages 
over  the  older  methods,  that  the  electric  drive  does 
over  the  older  methods  of  transmitting  power.  In 
nearly  every  industrial  operation  there  is  a  demand 
for  heat.  The  amount  of  power  required  is  usually 
relatively  small  compared  with  the  demand  for  heat. 
Many  new  industries  have  been  created  by  the  aid  of 
electric  heat  through  processes  not  otherwise  possi- 
ble. In  other  industries  it  has  resulted  in  increased 
production,  improved  product,  and  decreased  manu- 
facturing cost. 

Development  of  Field. — Only  the  general  exploi- 
tation of  proven  appliances  will  result  in  a  rational 
development  of  the  industrial  heating  field.  The 
adaptation  of  electric  heat  to  many  tools  and  appli- 
ances is  apparently  a  simple  proposition;  but  the  eco- 
nomical and  efficient  accomplishment  of  a  given  oper- 
ation calls  for  special  knowledge  comprising  science 
and  experience.  The  effect  of  correct  design  and  proper 
application  of  heating  devices  upon  the  future  success 
of  the  industrial  heating  business  cannot  be  overesti- 
mated. The  questions  of  heat  insulation,  thermal  stor- 
age and  thermal  load  factor  have  an  important  bearing 
upon  the  efficiency  and  economy  of  operation  that 
must  also  be  considered.    The  many  cases  where  heat- 


INDUSTRIAL     HEATING  131 

ing  elements  have  been  purchased  and  applied  to  appa- 
ratus of  various  kinds,  and  results  obtained  by  the 
crudest  methods,  are  not  entirely  desirable  from  the 
standpoint  of  rational  development,  but  they  furnish 
ample  evidence  of  the  tremendous  field  existing  for  the 
application  of  electric  heat. 

Advantages  of  Electric  Heat. — Safety,  conven- 
ience, flexibility  and  cleanliness  are  apparent  in  elec- 
tric heating  as  well  as  in  other  electrical  applications. 
Sanitary  conditions  are  improved  and  labor  is  made 
more  available  and  contented.  Machines  may  be 
placed  in  the  most  advantageous  positions  without 
regard  to  the  source  of  heat.  Constant  losses  due  to 
the  transmission  of  heat  are  eliminated.  Wide  ranges 
of  temperature  for  every  kind  of  industrial  work  are 
obtained.  Uniform,  yet  easily  controlled  tempera- 
tures which  are  not  readily  aflfected  by  air  drafts  are 
made  possible.  Any  amount  of  heat  may  be  generated 
efficiently,  at  any  desired  temperature,  and  under  any 
desired  atmospheric  conditions.  Ease  of  application, 
saving  of  labor  and  skill,  improvement  of  product  and 
reduction  in  floor  space  are  other  advantages  of  elec- 
tric heat. 

Comparison  with  Fuel  and  Steam  Heat. — Gas  or 

other  fuels  permit  application  of  high  temperatures 
but  the  heat  produced  is  irregular  and  the  flame  is 
accompanied  by  soot  and  fumes  which  soil  the  work, 
and  the  hot  vitiated  air  afifects  the  health  and  comfort 
of  the  operators. 

Steam  gives  a  uniform  heat,  but  the  temperature 
is  limited  by  the  safe  steam  pressure  that  may  be 
used.  The  accompanying  curve  and  table  shows  the 
gauge  pressure  required  to  produce  various  tempera- 
tures in  heating  devices. 

In  many  industries  where  steam  is  required  in 
large  quantities  for  low  temperature  work,  it  is  found 
advantageous  to  use  electricity  for  the  high  tempera- 
ture operations.  The  many  objections  to  the  produc- 
tion of  high  temperature  steam  in  manufacturing 
establishments  are  quite  obvious. 


132 


ELECTRIC     HEATING 


^50° 

too                  20O                   300              AOO 

Jr\ 

'     ■      yi 

425  ::: 

1  '            jT 

1     1        y 

AOO  '. '.  I 

H  37S  ::: 

1   / 

:::  ::  "::]i  j  "": :.   :""::":::::: 

:::  ::"i::"_.::.::  :::::::  ::':::: 

i  iSo  212 

/ 

z    :: : 

:::  at::  :::  ::::::_  :::::t"  ::   :: 

UJ      "  I 

/                ' 

3    :: : 

/ 

/ 

±:_:.  ::    :...:: .:  ..  

J    '.'-1. 

i 

"::::::::  .  ji'.z'.'.'.z'...'..'.X"-  "-'". 

j  . 

Temperature 

Pounds 

Fahr. 

Pressure 

376» 

172 

377 

174 

378 

176 

379 

178 

380 

180 

381 

183 

382 

185 

383 

188 

384 

190 

385 

193 

386 

195 

387 

198 

388 

200 

389 

203 

390 

205 

391 

208 

392 

210 

393 

213 

394 

216 

395 

218 

396 

221 

397 

224 

398 

226 

399 

229 

400 

232 

401 

235 

402 

238 

403 

241 

404 

244 

405 

247 

406 

250 

407 

253 

408 

256 

409 

259 

410 

262 

411 

265 

412 

268 

413 

271 

414 

275 

415 

278 

416 

281 

417 

285 

418 

288 

419 

291 

420 

294 

421 

297 

422 

300 

423 

303 

424 

307 

425 

310 

426 

313 

427 

316 

428 

319 

429 

322 

430 

326 

431 

330 

432 

334 

433 

338 

434 

342 

435 

346 

436 

350 

0  lOO  200  300  AOO 

GAUGE   PRESSURE  IN   LBS 

Curve  and  Table  showing  Gauge  Pressure  of  Saturated 
Steam  Corresponding  to  Increase  in  Temperature. 


Heating  Elements. — The  more  general  application 
of  electric  heat  has  been  delayed  materially  by  the 
tendency  to  call  for  specially  designed  apparatus  to 
meet  every  industrial  need,  in  place  of  modifying  the 
application  to  meet  the  conditions  of  standardized  heat 
units. 


INDUSTRIAL     HEATING  133 

Heating  elements  have  been  developed  by  differ- 
ent manufacturers  of  heating  devices  of  such  dimen- 
sions and  thermal  characteristics  as  to  be  readily  ap- 
plicable to  many  of  the  ordinary  arts  and  trades. 
Rectangular,  square,  and  round  flat  units,  tubular 
cartridge  units,  and  air  drying  or  heating  units  of  many 
shapes,  sizes,  and  capacities  are  available  for  various 
applications.  New  alloys,  improved  electrical  insu- 
lators of  high  thermal  conductivity,  and  the  more  in- 
telligent use  of  heat  insulating  materials,  have  done 
much  to  enlarge  the  possibilities  of  the  electric  heat- 
ing field. 

Heating  Specifications.  In  determining  the  ca- 
pacities of  various  industrial  heating  apparatus  it  is 
necessary  to  secure  comprehensive  data  on  the  spe- 
cific apparatus  to  which  electric  heat  is  to  be  applied, 
as  well  as  on  the  actual  working  conditions  which 
have  to  be  met.  The  following  will  illustrate  some 
of  the  points  that  have  to  be  considered  in  industrial 
problems : 

Heating  of  Water  or  Other  Liquids: 

(1)  Nature  of  liquid. 

(2)  Size  and  shape  of  vessel. 

(3)  Temperature  to  be  maintained. 

(4)  Time  allowed  for  heating  up. 

(5)  Amount  of  liquid  to  be  heated. 

(6)  Material  of  containing  vessel. 

(7)  Exterior  surface  of  containing  vessel   (light  or  dark, 
rough  or  polished.) 

(8)  Cover  of  vessel. 

(9)  Kind  and  thickness  of  heat  insulation. 

Heating   of  Ovens: 

(1)  Size  and  shape  of  oven. 

(2)  Cycle  of  heating  operation. 

(3)  Temperature  to  be  maintained. 

(4)  Weight  of  material  to  be  baked. 

(5)  How  material  is  handled. 

(6)  Duration  of  process. 

(7)  Number  of  bakes  required. 

(8)  Weight  of  trucks  carrying  material  into  oven. 

(9)  Character  of  oven  insulation.. 

(10)  Diameter  and  length  of  ventilating  flue. 


134  ELECTRIC     HEATING 

Electric  Furnaces: 

(1)  Maximum  temperature  required. 

(2)  Kind  of  work  to  be  done. 

(3)  Character  of  furnace  to  be  adopted. 

(4)  Size  and  shape  of  chamber  required. 

(5)  Quantity  of  work  to  be  undertaken. 

Branding   Irons: 

(1)  Size   and   nature   of   the   brand. 

(2)  Character  of  material. 

(3)  Wet  or  dry  material. 

(4)  Speed  required. 

(5)  Sample  of  material. 

Irons,  Glue  Pots,  etc.: 

(1)  Weight  and  size  of  devices  now  in  use. 

(2)  Class  of  work  to  be  done. 

(3)  Speed  required. 

Steam  Generators: 

(1)  Feed  water  temperature. 

(2)  Pressure  desired. 

(3)  Amount  of  steam  in  pounds  per  hour. 

(4)  Time  allowed  for  bringing  up  to  pressure. 

(5)  Dimensions  of  boiler. 

(6)  Character  and  construction  of  boiler. 

(7)  Boiler  insulation. 

Inasmuch  as  electric  energy  is  ordinarily  sold  on 
the  basis  of  maximum  demand,  as  well  as  on  that  of 
energy  consumption,  it  is  necessary  to  design  electric 
heating  apparatus  for  low  demand  and  long  hour  use, 
rather  than  high  demand  and  short  hour  use.  Ar- 
rangement for  off-peak  power  consumption  is  also 
desirable  when  conditions  will  permit. 

Apparatus  designed  with  minimum  wall  surface 
in  relation  to  content  will  obviously  be  more  efficient 
than  if  made  in  other  forms. 

Applications  of  Electric  Heat. — Perhaps  the  most 
important  application  of  electric  heat  is  found  in  the 
electrochemical  and  electrometallurgical  industries 
where  the  electric  furnace  has  revolutionized  some 
manufacturing  enterprises  and  actually  created  others. 

In  the  metal  trades  industry  electric  welding  appa- 
ratus, melting  tanks,  soldering  devices,  oil  tempering 


INDUSTRIAL     HEATING 


135 


baths,  annealing  furnaces,  and  various  types   of   self 
heated  tools  have  many  proven  advantages. 

Numerous  heating  operations  in  automobile,  print- 
ing and  publishing,  paper,  laundry,  confectionery,  and 
clothing  industries,  may  be  performed  with  a  greater 
degree  of  satisfaction  with  electricity  than  with  fuel 
methods. 

The  list  of  heating  applications  which  follows  will 
convey  a  general  impression  of  the  vast  extent  to 
which  electric  heat  may  be  applied  in  the  industrial 
field: 

Heating   Applications. 
Automob:ie  Factories  and  Garages: 


Vulcanizers. 
Varnish  drying  ovens. 
Welding  apparatus. 
Hood  heaters. 
Foot    warmers. 
Rectifier  tube  boilers. 
Solution  tanks. 
Disc  stoves. 

Barber  Shops: 
Water  heaters. 
Curling  irons. 
Sterilizers. 

Beauty  Parlors: 
Hair  dryers. 
Curling  irons. 
Disc  stoves. 

Boiler  Shops: 

Welding  machines. 
Soldering  irons. 

Bookbinding  Shops: 
Matrix   dryers. 
Embossing   and   stamping 

presses. 
Drying  closets. 
Back  shapers. 
Palette  heaters. 

Breweries: 

Vat  dryers. 

Glue  and  resin  heaters. 


Enameling  furnaces. 
Soldering  irons. 
Branding  irons. 
Steering  wheel  warmers. 
Varnish  tank  heaters. 
Hardening  furnaces. 
Oil  tempering  baths. 


Cigar  lighters. 
Hair  dryers. 
Disc  stoves. 

Cauterizers. 
Water  heaters. 
Die  tank  heaters. 

Hardening  and  annealing 
furnaces. 

Branding  irons. 

Glue  pots. 

Case   making  and   covering 

machines. 
Back  rounders. 
Gilding  wheel  heater. 


Branding  irons. 


136 


ELECTRIC     HEATING 


G.  E.  Cigar  Lighter, 


Brush   Manufacturers: 

Glue  pots. 

Tank  heaters. 
Button  Manufacturers: 

Hot  plates. 

Japanning  ovens. 
Cann^'ng    Factories: 

Can  capping  machines. 

Soldering  pots. 
Cigar  Stores: 

Cigar  lighters. 
Cleaning  and  Dyeing  Works: 

Tailor  irons. 

Hot  plates. 
Cloak  and  Suit  Manufacturers: 

Tailor  irons. 

Velvet  marking  irons. 
Coffee  and   Tea   Merchants: 

Percolators. 

Water  heaters. 

Coffee  roasters. 
Colleges  and  Schools: 

Laboratory   devices    (listed 
elsewhere.) 

Hot   plates    (domestic    sci- 
ence.) 
Confectioners: 

Hot  plates. 

Chocolate   warmers. 

Dipping  tanks. 

Corn  poppers. 


Branding  irons. 
Flat  irons. 

Button  die  heaters. 
Celluloid   softeners. 

Soldering  irons. 
Branding  irons. 

Branding  irons. 

Laundry  irons. 
Puff  irons. 

Laundry  irons. 
Puff  irons. 

Tea  pots. 
Hot  plates. 


Ovens  (domestic  science.) 
Water  heaters. 


Batch   warmers. 
Chocolate  trays. 
Water  heaters. 
Ovens. 


INDUSTRIAI.     HEATING 


137 


Contractors   and    Builders: 
Branding  irons. 
Soldering  pots. 

Corset  Factory: 

Corset  irons. 
Disc  stoves. 


Soldering   irons. 
Glue  pots. 

Form  heaters. 
Flat  irons. 


G.  E.  Glue  Pots  in  Box  Factory, 


Creameries  and   Dairies: 
Water  heaters. 
Hot  plates. 

Dentists: 

Cauterizers. 
Hot  plates. 
Vulcanizers. 


Sterilizers. 


Sterilizers. 
Dental  furnaces. 


138 


ELECTRIC     HEATING 


Department  Stores: 

Cigar  lighters. 

Hot  plates. 
Doctors: 

Sterilizers. 

Hot  bath  cabinets. 

Water  heaters. 


Pyrograph  needles. 
Flat  irons. 

Cauterizers. 

Heating  pads  and  blankets. 

Incubators. 


G.    E.    Irons   in   Cleaning   and   Dyeing    Establishment. 


Dress  Goods  Factory: 

Pleating  machines. 

Flat  irons. 
Drug  Stores: 

Cauterizers. 

Sterilizers. 

Sealing  wax  heaters. 
Electrotypers: 

Heating  furnaces. 

Solder  pots. 
Factories  (General): 

Welding  machinery. 

Branding  irons. 

Glue  pots  and  cookers. 

Pitch  kettles. 

Farms: 

Incubators  and  brooders. 
Soldering  irons. 
Hot  plate?. 


Ironing  machines. 
Velvet  marking  irons. 

Water  heaters. 

Cigar  lighters. 

Paper  seal  moisteners. 

Soldering  irons. 
Water  heaters. 

Soldering  irons. 
Water  heaters. 
Solder  pots. 
Pouring  pots. 


Branding  irons. 
Sterilizers. 
Fbod  warmers. 


INDUSTRIAL     HEATING 


139 


Foundries: 

Steel  furnacts. 
Welding  machinery. 
Soldering  irons. 

Furniture  Factories: 
Wax  knife  heater. 
Glue  pots. 

Hair  Dressers: 

Hair  dryers. 
Water  heaters. 

Harness  Shops: 
Branding  irons. 
Water  heaters. 

Hat  Manufacturers  and  Stores: 

Flanging  bags. 
Velouring  stoves. 
Machine   irons. 

Hospitals  and   Sanitariums: 

Cauterizers. 
Sterilizers. 
Water  heaters. 
Mangles. 

Hotels: 

Sealing  wax  heaters. 
Hot  bath  cabinets. 
Tailors'  irons. 
Hot  plates. 
Cigar   lighters. 

Jewelry  Stores: 

Small  drying  ovens. 

Hot  plates. 
Knitting  Mills: 

Hosiery  forms. 

Yarn  conditioning  ovens. 

Laboratories: 

Annealing  and  enameling 

furnaces. 
Sterilizers. 
Disc  stoves. 
Tube,  crucible,  vacuum,  and 

muffle  furnaces. 


Metal  melting  tanks. 
Core  ovens. 
Solder  pots. 

Wax  burning-in   iron. 
Drying  ovens. 

Curling  irons. 
Disc  stoves. 


Wax  heaters. 
Creasing  irons. 

Hand  flats. 
Hand  shells. 
French  irons. 


Hot  cabinets. 
Heating  pads. 
Flat  irons. 
Incubators. 

Laundry  irons. 
Curling  irons. 
Heating  pads. 
Water  heaters. 
Towel  dryers 


Sealing  wax  heaters. 
Soldering  irons. 

Flat  irons. 


Flask  heaters. 
Shelf  heaters. 
Water  heaters. 
Soldering  irons. 
Test  tube  heaters. 
Bacteriological    incubators. 


140 


ELECTRIC     HEATiNLi 


i_aundries: 

Sleeve  irons. 

Collar   and   cuff  moulding 

machinery. 
Ironing  machines  and  rolls. 
Starch  cookers. 


Puff  irons. 
Laundry  irons. 
Marking  machines. 
Steam   boilers. 
Clothes  dryers. 


Installation    of    Simplex   Laiindry    Irons    Equipped 
with   Suspension  Cords. 


Leather  Factories: 

Leather  creasing  tools. 
Glue   and   wax  heaters. 
Embossing  machines. 
Crimping  machines. 

Libraries: 

Sealing  wax  pots. 
Paper  seal  moisteners. 

Machine  Shops: 

Welding  machinery. 
Soldering  irons. 
Metal  melting  tanks. 
Branding  irons. 


Solution  tanks. 
Branding  irons. 
Flat  irons. 
Wax  knife  heaters. 


Envelope  gum  dryers. 
Glue  pots. 

Oil  tempering  tanks. 
Solder  pots. 
Solution  tanks. 
Oven  furnaces. 


INDUSTRIAL.     HEATING 


141 


Offices : 

Sealing-wax  heaters. 
Paper  seal  moisteners. 

Paper  Box  Factories: 
Box   mould  heaters. 
Sealing  wax  heaters. 
Drying  ovens. 

Photographers: 
Burnishers. 
Glue  pots. 
Fan  dryers. 
Flat  irons. 

Piano  Stores  and  Factories: 

Drying  ovens. 

Glue  pots  and  cookers. 

Solution  tanks. 

Plumbers  and  Tinsmiths: 

Roofing  pitch  kettles. 
Solder  pots. 

Peanut  and  Popcorn  Stands: 

Peanut  roasters. 
Popcorn  poppers. 

Printers  and  Publishers 

Linotype  and  monotype  pots 
Metal  melting  tanks. 
Matrix   dryers. 
Back  rounders. 
Embossers. 

Printing  press  heaters. 
Branding  irons. 
Wax-heating  kettles. 

Restaurants: 

Coffee  urns. 
Toasters. 
Food  warmers. 
Bake  ovens. 
Griddles. 
Cigar  lighters. 

Roofers: 

Branding  irons. 
Solder   pots. 


Envelope   gum  dryers. 
Water  stills. 


Glue  pots. 
Branding  irons. 
Disc  stoves. 


Film  and  print  dryers. 
Branding  irons. 
Wax  heaters. 
Disc  stoves. 

Branding  irons. 
Soldering  irons. 
Annealing  furnaces. 

Pipe  thawing  apparatus. 
Soldering  irons. 


Peanut  warmers. 
Butter  warmers. 

Glue  pots  and  cookers. 
Back  shapers. 
Palette  heaters. 
Printing  ink  heaters. 
Drying  rooms. 
Stamping  and  embossing 

presses. 
Wax-stripping  tables. 

Waffle  irons. 
Plate  warmers. 
Steam  tables. 
Broilers. 
Egg  boilers. 


Soldering  irons. 
Pitch  kettles. 


142 


ELECTRIC     HEATING 


Linotype  Machine  Equipped  with  Coin  Melting  Pot. 


Saloons: 

Hot  plates. 
Cigar  lighters. 
Plate  warmers. 

Ship  Building  Yards: 
Welding  machines. 
Soldering  irons. 

Shirt  Factories: 
Laundry  irons. 
Ironing  machines. 
Disc   stoves. 
Flat  irons. 


Water  heaters. 
Percolators. 


Glue  pots  and  cookers. 
Branding  irons. 

Tailors'  irons. 
Cuff  and  collar  moulding 
machines. 


INDUSTRIAL     HEATING 


143 


Shoe  Factories  and  Stores: 
Thread  waxing  machines. 
Lining  cementer. 
Stitchers. 

Embossing  machines. 
Welters. 
Branding  irons. 
Flat   irons. 
Turn  and  welt  machines. 


Knurling  machines. 

Patent  leather  repairers. 

Indenters  and  burnishers. 

Embossers. 

Glue  pots  and  cookers. 

Shoe  relasters. 

Wax  knife  heaters. 


G.  E.  No.   3  Oil  Tempering  Bath  in  Atlas-Ball 
Plant,  Philadelphia. 


Steel  Mills: 

Welding   machinery. 
Oil  tempering  tanks. 


Steel  furnaces. 


144 


ELECTRIC     HEATING 


Street  Railway  Shops: 
Car  heaters. 
Soldering  irons. 
Water  heaters. 

Tailor  Shops: 
Tailors'  irons. 
Clothes  dryers. 

Theatres: 

Water  heaters. 
Curling  irons. 

Turkish  Baths: 
Hair  dryers. 
Hot  bath  cabinets. 

Wagon  Shops  and  Factories: 

Vulcanizers. 
Branding  irons. 
Soldering  irons. 

Wood  Workers  and  Carpenters: 
Branding  irons. 
Wax  melters. 


Welding  machinery. 
Solder  pots. 
Branding  irons. 

Puff  irons. 


Grease-paint  heaters. 


Water  heaters. 
Curling  irons. 

Welding  machines. 
Glue  pots  and  cookers. 
Disc  stoves. 

Glue  pots. 
Soldering  irons. 


CHAPTER  X 

ELECTRIC  FURNACES. 

Economic  Advantages. — The  use  of  electric  en- 
ergy for  producing  furnace  heat  has  revolutionized 
many  modern  industries.  The  field  which  it  has  cre- 
ated in  the  development  of  electrochemical  and  metal- 
lurgical processes  has  great  possibilities.  Not  only 
does  the  electric  furnace  afford  opportunity  for  im- 
proving and  widening  these  industries,  but  its  use 
requires  large  quantities  of  electric  power,  the  devel- 
opment of  which  produces  a  market  for  energy  that 
might  otherwise  lie  dormant  or  go  to  waste.  Further- 
more it  improves  the  load  factor  and  diversity  of  large 
central  station  loads,  and  otherwise  tends  to  foster 
greater  economic  wealth. 

Only  high  temperature  furnaces  for  melting  and 
refining  various  substances  will  be  considered  in  this 
chapter.  The  general  design,  manner  of  operation, 
and  field  of  application  of  electric  furnaces  will  be  out- 
lined so  as  to  convey  an  understanding  of  the  sub- 
ject. 

The  Electric  Furnace  Field. — The  application  of 
the  electric  furnace  has  made  it  possible  to  manufac- 
ture a  number  of  substances  that  would  otherwise  not 
be  available  for  commercial  purposes  if  combustion 
methods  were  the  sole  means  of  production.  None 
other  than  electric  furnace  methods  have  ever  been 
successfully  employed  in  the  manufacture  of  such  well 
known  substances  as  carborundum,  aluminum,  and  cal- 
cium carbide.  Immense  industries  have  been  built  up, 
and  great  quantities  of  power  employed  for  their  pro- 
duction. There  are  many  other  processes  that  may  be 
performed  only  with  the  electric  furnace,  but  the  ex- 
tensive applications  of  which  are  limited  by  the  cost 
of  production.  There  is  little  doubt  but  that  more 
of  the  supply  of  nitrogen  required  for  soil  fertilization 


146  ELECTRIC     HEATING 

will  be  drawn  from  the  air  by  electric  furnace  appa- 
ratus, as  the  present  rapidly  depleting  natural  nitrate 
deposits  become  exhausted.  Several  plants  located 
where  electric  energy  is  cheaply  produced,  now  man- 
ufacture great  quantities  of  nitric  acid  and  nitrates 
and  consume  enormous  amounts  of  power. 


Pouring    From    Snyder   Steel    Furnace. 

The  electric  furnace'  may  create  temperatures 
greatly  in  excess  of  those  otherwise  available.  With 
present  apparatus  operating  temperatures  as  high  as 
6500°  F.  ma}^  be  attained.  The  exclusion  of  objection- 
able furnace  gases  and  air,  makes  it  possible  to  per- 
form many  new  operations.  The  smelting  of  various 
metallic  ores  that  formerly  could  not  be  handled  sat- 
isfactorily or  economically  has  been  made  possible. 

Probably  the  greatest  field  for  utilizing  the  elec- 
tric furnace,  at  the  present  time,  is  in  its  application 
to  such  processes  as  are  now  largely  performed  with 
fuel  burning  furnaces.     It   is   in   this   field,   however. 


ELECTRIC     FURNACES  147 

that  the  electric  method  has  to  compete  on  the  basis 
of  both  cost  and  quality  of  product. 

Character  of  Furnace  Power  Loads. — Some  con- 
cerns using  electric  furnaces  do  not  attempt  twenty- 
four  hour  operation  on  account  of  the  usual  ineffi- 
ciency of  night  work.  This  is  especially  true  of  those 
engaged  in  steel  manufacturing.  Some  furnaces  have 
to  be  shut  down  while  the  products  are  removed  and 
new  charges  introduced.  The  resulting  load  factor  is 
relatively  high,  however,  as  compared  w^ith  average 
central  station  motor  service. 


G.    E.    Laboratory    Tube    Furnace.      (Max.    temp.    1832°  F., 
2y2      in.      diameter,      various  lengths.) 

Some  smaller  furnace  installations  may  be  shut 
down  from  three  to  four  hours  per  day  without  seri- 
ous disadvantage  and  this  condition  often  makes  it  pos- 
sible to  utilize  off-peak  power.  Where  steel  melting 
furnaces  are  used,  it  has  been  found  advisable  in  many 
instances  to  mould  during  the  day  and  melt  at  night. 
This  practice  has  developed  an  all-night  furnace  load 
for  the  power  company. 

The  variations  in  current  in  an  electric  furnace 
are  usually  due  to  changes  in  condition  of  the  charge. 
Some  furnaces  are  operated  in  series  with  a  ballast. 
For  direct  current  service  the  ballast  has  to  be  a 
resistance,  whereas  for  alternating  current  service  a 
resistance  or  a  reactance  may  be  used.  The  power 
factor  of  induction  furnaces  is  generally  low.  It  may 
be  raised  by  lowering  the  frequency,  or  by  using  a 
synchronous  motor  as  a  condenser. 

Character  of  Service  Required. — Alternating  cur- 
rent is  used  in  furnace  work  more  often  than  direct 
current.  For  induction  furnace  operation  alternating 
current  is  employed,  whereas  direct  current  is  required 


148  ELECTRIC     HEATING 

in  electrolytic  furnaces.  In  most  arc  and  resistance 
furnaces  either  alternating  or  direct  current  may  be 
employed. 

The  voltage  required  for  furnace  work  is  gen- 
erally low  (50  to  200)  although  in  nitrogen  furnaces 
pressures  as  high  as  5,000  to  10,000  volts  are  often 
utilized.  The  size  of  furnace  loads  usually  makes  it 
necessary  to  reduce  the  voltage  at  the  point  of  deliv- 
ery, and  consequently   almost  any  available   primary 


G.  E.  Crucible  Furnace.  (Max. 
temp.,  1112°  F.,  crucible  1 
in.   by   2   in.   high.) 

voltage  may  be  used.  The  higher  the  voltage  applied 
the  less  is  the  current  required,  the  smaller  the  elec- 
trode cross  section,  and  the  less  the  heat  conducted 
out  of  the  furnace  through  the  electrode.  Voltages  are 
limited,  however,  from  considerations  of  the  safety 
of  operators. 

Arc  and  resistance  furnaces  are  usually  built  for 
60  cycle  operation  in  sizes  under  1000  kilowatts.  Larger 
furnaces  are  generally  constructed  for  lower  fre- 
quencies. Induction  type  furnaces  usually  require  spe- 
cial low  frequencies  in  sizes  larger  than  500  kilowatts 
capacity. 

Most  furnaces  are  operated  with  single-phase 
service.  The  larger  resistance  furnaces  for  manufac- 
turing chemical  products,  graphite,  and  carbide  use 
single-phase  service.  Nitrogen  fixation  furnaces  are 
generally  connected  so  as  to  use  three-phase  current. 
Two  and  three-phase  energy  is  frequently  utilized  in 
steel  making  although  it  is  contended  by  some  manu- 
facturers  that   single-phase   service   is   more   efficient 


ELECTRIC     FURNACES 


149 


and  satisfactory  from  the  standpoint  of  furnace  oper- 
ation. A  single  electrode  furnace  is  somewhat  cheaper 
and  more  readily  manipulated;  the  heat  losses  are 
less;  and  the  electrode  and  refractory  roof  costs  are 
smaller.  On  the  other  hand,  most  power  producers 
prefer  to  deliver  two  or  three-phase  energy  for  obvious 
reasons.  Central  station  companies  having  4-wire, 
three-phase  distribution  systems  are  sometimes  able  to 
supply  single-phase  service  by  suitable  arrangement  of 
tranformer  connections. 

Classification  of  Electric  Furnaces. — Electric  fur- 
naces may  be  divided  into  two  general  classes,  the 
resistance  type,  and  the  arc  type.  It  is  often  difficult 
to  distinguish  the  class  to  which  different  furnaces 
belong,  because  both  the  heat  of  the  arc,  and  the  heat 
resulting  from  the  resistance  to  the  flow  of  current, 
are  frequently  utilized  in  heating  the  charge. 


y////////////////////////. 

NSl/LATING    WALL;;^ 


Tube    Furnace. 

Resistance  type  furnaces  may  derive  heat  from 
the  passage  of  current  through  resistance  wires, 
through  other  resistance  materials  surrounding  the 
charge,  or  by  the  passage  of  current  through  the 
charge  itself.  Examples  of  furnaces  employing  re- 
sistance wires  as  a  means  for  heating  the  charge  are 
found  in  the  ordinary  small  crucible,  tube,  and  muffle 
type  furnaces  often  used  in  laboratories  for  operation 
at  temperatures  under  1800°  F.  Typical  examples 
of  the  second  type  of  resistance  furnaces  are  those  of 
the  Acheson  carborundum  furnace  and  some  of  the 
w^ell  known  high  temperature  electric  crucible  fur- 
naces. The  induction  type  furnace,  wherein  a  current 
is  induced  in  the  charge  by  electromagnetic  induction, 


150  ELECTRIC    HEATING 

is  one  of  the  best  examples  of  the  third  type  of  resist- 
ance furnace.  A  sharp  distinction  between  these  three 
classes  is  often  impossible  because  some  types  involve 
more  than  one  principle  in  their  design. 


Furnace  With  Resistance  in  the  Charge. 

Arc  furnaces  may  be  divided  into  three  classes, 
the  principles  of  which  may  or  may  not  be  combined 
in  one  type  of  apparatus.  The  first  class,  known  as 
the  direct  arc  furnace,  produces  heat  by  causing  an  arc 
between  the  electrode  and  the  charge.  The  second 
class  known  as  the  series  arc  furnace  passes  current 
from  one  electrode  to  the  charge  and  from  the  charge 
back  to  another  electrode.  The  third  class,  known 
as  the  indirect  arc  furnace,  produces  heat  between 
electrodes  supported  above  the  charge. 

A  more  complete  classification  of  electric  furnaces 
is  given  by  Stansfield  in  his  excellent  text  on  *'The 
Electric  Furnace"  as  follows : 

Classification  of  Electric  Furnaces. 

(1)  Resistance  Furnaces. 

(a)  Using  special  resistance. 

(1)  Resistance  wires  in  furnace  walls    (tube  fur- 
nace.) 

(2)  Resistance  material   in    the    charge     (carbor- 
undum furnace.) 

(b)  No  special  resistance. 

(1)  Electrolytic   (aluminum  furnace.) 

(2)  Using  charge  as  resistance. 

(a)  Solid  material  (graphite  furnace.) 

(b)  Melting  material    (Heroult   smelting   fur- 
nace.) 

(c)  Liquid  material  (induction  furnace.) 

(2)  Arc  furnaces. 

(a)  Direct  arc. 

(1)  Single  arc   (Girod  furnace.) 

(2)  Series  arc  (Heroult  furnace.) 

(b)  Indirect  ore  (Stassano  furnace.) 


ELECTRIC     FURNACES 


151 


fU^EDrLECTROLYTE 


Aluminum  Furnace. 

Advantages  and  Limitations  of  Electric  Furnaces. 
The  increased  range  of  temperatures,  the  easy  con- 
trol of  the  heat  generated,  the  exclusion  of  harmful 
ingredients,  and  the  careful  adjustment  of  atmosphere 
conditions,  make  the  electric  furnace  ideal  for  many- 
electrochemical  operations. 


ELECTROPE 
Shaft  Furnace. 


Comparisons  are  sometimes  made  between  the 
cost  of  fuel  and  the  cost  of  electricity  and  these  fig- 
ures used  as  a  basis  for  deciding  what  method  of  heat- 
ing should  be  employed.     In  so  doing  some  important 


152  ELECTRIC     HEATING 

considerations  are  frequently  overlooked.  In  the  first 
place,  the  efficiency  of  a  furnace  is  the  ratio  between 
the  heat  beneficially  utilized,  and  the  heat  energy 
supplied.  The  average  efficiencies  of  a  number  of  dif- 
ferent types  of  furnaces  are  given  on  good  authority 
as  follows : 

Average  Efficiency 
Furnaces  Per  cent. 

Coke   fired    crucible    steel    furnaces 2.5 

Metal    melting    reverberatory    furnaces 12.0 

Open-hearth   steel   furnaces 25.0 

Shaft  furnaces    40.0 

Large   electric   furnaces 75.0 

It  is  apparent  that  although  the  number  of  heat 
units  made  available  in  the  fuel  furnace  may  exceed 
those  in  the  electric  furnace  for  the  same  expenditure 
of  money,  the  higher  efficiency  of  the  latter  may  prove 
its  superiority. 


Induction    Furnace. 


Heat  Energy  Required. — The  heat  consumed  in 
the  electric  furnace  is  utilized  and  dissipated  as 
follows : 

(1)  To  raise  starting  materials  to  temperature 
of  reaction. 

(2)  To  change  the  state  of  the  substance  as  re- 
quired. 

(3)  To  provide  energy  for  the  reaction. 

(4)  To  supply  the  conduction  and  radiation 
losses. 


ELECTRIC     FURNACES 


153 


The  first  item  may  be  calculated  by  multiplying 
the  weight  of  the  charge,  the  temperature  difiference, 
and  the  mean  specific  heat.  The  second  may  be  ob- 
tained by  multiplying  the  weight  of  the  charge  by  the 
latent   heat   of  fusion,   vaporization,    or    sublimation, 


Direct    Heating    Arc    Furnace. 


according  as  it  is  required  to  change  from  solid  to 
liquid,  liquid  to  vapor,  or  solid  to  vapor  respectively. 
The  third  may  or  may  not  absorb  useful  heat  energy 
and  in  some  cases  actually  produces  heat  within  the 
charge  which  reduces  the  amount  of  outside  energy 
required. 

Conduction  losses  take-  place  mainly  through  the 
furnace  walls  and  throug'h  the  electrodes.  The  heat 
losses  through  the  walls  depend  upon  the  thermal 
conductivity  and  area  of  the  walls  and  the  difiference 
in  temperature  inside  and  outside  the  furnace.  Heat 
losses  through  the  electrodes  depend  upon  their  ther- 
mal as  well  as  upon  their  electrical  conductivity,  for 
the  reason  that  heat  is  conducted  from  the  hot  to  the 
cold  ends,  and  generated  in  the  electrodes  by  the  pass- 
age of  current.  The  radiation  losses  depend  upon  the 
outside  area  of  the  furnace,  the  character  of  its  sur- 
face, and  the  difiference  in  temperature  between  its 
surface  and  that  of  the  surrounding  atmosphere. 

Furnace  Walls. — In  the  choice  of  material  for 
furnace  walls  four  properties  of  the  substance  are 
generally  considered : 


154 


ELECTRIC     HEATING 


(1)  Its  fitness  for  the  chemical  nature  of  the  re- 
action ; 

(2)  Maximum  temperature  it  is  required  to  with- 
stand ; 

(3)  Its  thermal  conductivity; 

(4)  Its  ability  to  withstand  expansion  and  con- 
traction. 

For  a  basic  charge  a  basic  refractory  is  required 
and  for  an  acid  charge  an  acid  lining  is  essential. 


Direct  Heating-  Series  Arc    Furnace. 


Metallurgical  Furnace  Refractories. 

Basic  Lining.  Acid  Lining.  Neutral  Lining. 

Bauxite  Silica  Carbon 

Magnesia  Fire  clays 

Dolomite  Chromite 

Lime 

For  higher  temperature  furnace  work  certain  com- 
pounds of  carbon  and  silicon  as  well  as  pure  carbon 
are  especially  adaptable.  Pure  magnesia  is  recom.- 
mended  for  some  purposes. 

Furnace  walls  are  usually  constructed  of  two 
layers — the  inner  one  capable  of  withstanding  the  max- 
imum temperature  and  the  chemical  effects  of  the 
charge,  and  the  outer  one  of  high  heat  insulating 
quality. 

Furnace  Electrodes. — All  electric  furnaces,  with 
the  exception  of  induction  apparatus,  require  the  use 
of  electrodes  for  introducing  electric  energy  into  them. 


ELECTRIC     FURNACES 


155 


I 


The  most  desirable  qualifications  of  an  electrode  may 
be  enumerated  as  follows : 

(1)  Good  electrical  conductor. 

(2)  Poor  heat  conductor. 

(3)  High  melting  or  sublimation  point. 

(4)  Lack    of   contaminating   effect    upon    charge. 

(5)  Mechanical  strength. 

(6)  Cheapness. 

The  relative  importance  of  these  qualifications 
depends  largely  upon  the  kind  of  furnace  to  which 
the  electrodes  are  applied.     On  account  of  the  losses 


Independent     Arc     Furnace. 


that  take  place  through  the  electrodes  it  is  essential 
that  the  dimensions  and  material  be  carefully  con- 
sidered. The  consumption  of  electrode  material  in 
the  furnace  is  another  feature  that  has  much  to  do 
with  the  furnace  operating  costs. 

Electrodes  are  usually  made  of  carbon.  Graphite 
electrodes  have  the  advantages  of  better  resistance  to 
oxidation,  higher  electrical  conductivity,  and  greater 
purity,  but  they  are  more  expensive. 


CHAPTER  XI 

ELECTRIC  FURNACE  APPLICATIONS. 

Fundamental  Considerations  of  Commercial  En- 
terprises.— The  ultimate  success  of  any  industry  based 
on  the  application  of  the  electric  furnace  may  depend 
upon  any  one  of  a  number  of  local  conditions : 

(1)  Availability,  character,  and  cost  of  raw  ma- 
terials. 

(2)  Cost  of  transporting  raw  materials  to  furnace. 

(3)  Availability  and  cost  of  electric  power. 

(4)  Availability,  character,  and  cost  of  labor. 

(5)  Cost    of    transporting    finished     product     to 
market. 

(6)  Extent,  stability,  and  competitive  conditions 
of  market. 

A  casual  observer  is  likely  to  assume  that  any  en- 
terprise requiring  the  application  of  the  electric  fur- 
nace depends  solely  upon  cheap  power  for  its  success. 
That  random  conclusions  of  this  sort  are  often  mislead- 
ing may  be  observed  by  applying  the  above  six  con- 
siderations to  almost  any  commercial  electric  furnace 
project.  It  is  true  that  electric  equipments  producing 
large  quantities  of  cheaper  grade  products  in  competi- 
tion with  fuel  apparatus  often  require  very  low  power 
rates  to  insure  success.  On  the  other  hand  many  re- 
fining processes  are  carried  on  to  advantage  where 
power  costs  are  not  extremely  low. 

The  availability  of  raw  materials,  the  proximity  and 
cheapness  of  water  transportation,  and  the  labor  and 
market  conditions,  considered  aside  from  power  cost, 
have  each  had  a  potent  influence  in  determining  the 
feasibility  of  locating  electric  furnace  enterprises  at 
Niagara  Falls,  and  in  France,  Norway,  Sweden,  and 
Switzerland. 

Production  of  Ferro-AUoys. — Iron  alloyed  with 
chronium,  tungsten,  manganese,  silicon,  etc.,  is  known 


ELECTRIC     FURNACE     APPLICATIONS  157 

as  a  ferro-alloy.  It  is  somewhat  similar  to  cast  iron, 
but  differs  in  that  some  of  the  metals  or  other  ma- 
terials have  replaced  part  of  the  iron.  The  chief  use 
of  ferro-alloys  is  in  the  production  of  steel.  The  con- 
stituents are  usually  less  costly  to  obtain  in  ferro- 
alloys than  in  the  pure  state.  The  small  quantity  of 
iron  with  which  they  are  alloyed  simply  mixes  with 
the  charge  in  the  furnace  during  the  process. 

Most  of  the  ferro-alloys  are  produced  by  reduc- 
ing the  metallic  oxide  with  iron  or  iron  ore  and  carbon. 
Ferro-silicon  is  made  by  smelting  a  mixture  of  sili- 
con, in  the  form  of  quartz  or  quartzite,  with  carbon, 
and  iron  or  iron  ore.  The  latter  is  of  great  value  in 
the  production  of  steel  where  it  acts  both  as  a  de- 
oxidizer  and  as  a  preventive  of  objectionable  blow- 
holes in  steel  castings. 

The  electric  furnace  has  proven  itself  far  superior 
to  fuel  furnaces  in  the  production  of  ferro-alloys  be- 
cause of  the  higher  and  more  easily  controlled  tem- 
peratures it  affords,  and  on  account  of  the  absence  of 
objectionable  ingredients,  and  the  higher  percentage 
of  desirable  constituents  in  the  product.  The  manu- 
facture of  many  ferro-alloys  formerly  considered  com- 
mercially impractical  have  been  undertaken  since  the 
application  of  the  electric  furnace  has  become  more 
fully  understood.  The  production  of  silicon,  which 
is  of  great  value  to  the  chemical  industry  on  account 
of  its  resistance  to  the  action  of  acids,  was  formerly 
carried  on  on  a  very  small  scale  but  is  now  manufac- 
tured extensively  by  electric  furnace  methods.  Many 
thousands  of  horsepower  are  now  devoted  to  the  pro- 
duction of  ferro-alloys  and  silicon  in  the  electric  fur- 
nace. Vertical  electrode  type  crucible  or  ore  smelting 
furnaces  are  usually  employed  for  this  work. 

Smelting  of  Iron  Ores. — The  electric  furnace  is 
being  employed  to  some  extent  in  the  production  of 
pig  iron.  In  Sweden,  about  40,000  h,p,  are  utilized  in 
this  industry.  The  more  recently  developed  processes 
have  proved  technically  successful,  and  in  localities 
where  fuel  cost  is  high  and  conditions  are  such  that 
electric  energy  can  be  supplied  at  low  rates,  the  field 


158  ELECTRIC     HEATING 

of  application  of  the  pig  iron  furnace  is  large.  The 
average  amount  of  energy  required  has  been  found 
to  be  between  1800  and  2000  k\v  -hr.  per  ton  of  iron 
smelted. 


Iron  Smelting-  Furnace  at  Heroult,  Cal.   (capacity 
2400  kw.,   20  tons  per  day). 

Whereas  fuel  is  used  in  a  blast  furnace  for  pro- 
ducing heat  for  the  reduction  of  iron  oxide  it  is  only 
required  in  the  electric  furnace  for  the  latter  purpose. 
The  amount  of  fuel  required  is  therefore  at  least  70 
per  cent  less  and  a  much  inferior  quality  may  be  used. 

Many  types  of  furnaces  have  been  developed  for 
the  smelting  of  iron  ores.  They  all  consist  of  refrac- 
tory smelting  chambers  provided  with   two  or  more 


ELECTRIC     FURNACE     APPLICATIONS  159 

electrodes.  A  shaft  mounted  above  the  smelting 
chamber  is  filled  with  ore,  flux,  and  fuel  which  grad- 
ually moves  downward  as  the  materials  are  melted. 
Heat  is  produced  by  the  current  passing  between  the 
electrodes  through  the  charge. 

Smelting  of  Copper,  Zinc  and  Other  Metals. — A 
discussion  of  the  feasibility  of  producing  iron  and 
steel  is  given  elsewhere.  The  reduction  of  ores  of 
copper,  tin,  lead,  and  other  metals,  is  accomplished 
by  smelting  them  with  fuel.  The  electrical  method 
may  be  adopted  in  a  number  of  places  where  fuel  cost 
is  high  and  power  cost  is  low  as  it  has  been  found 
that  the  reduction  can  be  carried  on  more  accurately 
in  the  electric  furnace  than  in  fuel  fired  furnaces. 

On  account  of  the  volatility  and  the  ease  of  oxi- 
dation of  zinc,  serious  difficulties  have  been  encoun- 
tered in  the  treatment  of  the  ores.  The  electric  fur- 
nace method  has  actually  been  adopted  to  some  extent 
and  the  ores  smelted  satisfactorily.  Great  hopes  are 
entertained  by  authorities  on  the  subject  of  ore  treat- 
ment for  the  electric  zinc  smelting  furnace  because  of 
present  difficulties  with  fuel  apparatus,  and  on  account 
of  the  success  already  attained  with  the  electric  instal- 
lations. 

Production  of  Graphite  and  Carbide. — Graphite 
is  produced  in  the  Acheson  furnace  by  subjecting  a 
charge  of  carbonaceous  material  (usually  ground  an- 
thracite coal)  surrounding  a  graphite  or  carbon  core, 
to  great  heat.  At  Niagara  Falls,  N.  Y.,  several  million 
pounds  of  graphite  are  annually  produced  in  this  man- 
ner. 

Carborundum  is  produced  by  heating  a  mixture  of 
coke,  silicious  sand,  salt,  and  sawdust.  The  coke  is 
used  as  a  conducting  core  to  start  the  flow  of  current. 
The  output  of  carborundum  in  1905  was  nearly  six  mil- 
lion pounds,  and  about  7,000  h.p.  was  utilized  in  its 
production.  It  is  said  that  about  7600  kw  -hr.  are 
required  per  ton  of  carborundum  manufactured. 

Calcium  carbide  is  produced  in  great  quantities  in 
the  electric  furnace  for  making  acetylene.  It  may  also 
be  used  in  the  production  of  calcium   cyanamide  by 


160  ELECTRIC     HEATING 

heating  it  with  nitrogen  and  in  the  production  of  am- 
monia by  passing  steam  over  the  red  hot  carbide.  The 
former  is  of  use  as  a  fertilizer  and  the  latter  may  be 
made  into  ammonium  sulphate  for  the  same  purpose. 
The  total  production  of  calcium  carbide  in  the  electric 
furnace  amounted  to  about  250,000  tons  in  1909.  Sev- 
eral types  of  so-called  ingot  furnaces  and  resistance 
furnaces  have  been  developed  for  this  purpose.  About 
6000  kw  -hr.  are  usually  required  per  ton  of  product. 

Electrolytic  Furnace  Processes. — When  a  direct 
current  is  passed  through  a  fused  salt  electrolytic 
action  may  take  place.  The  metal  of  the  salt  is  liber- 
ated at  the  cathode,  or  negative  electrode,  whereas  the 
remainder  of  the  salt  is  liberated  at  the  anode.  The 
principles  that  apply  to  the  electrolysis  of  fused  salts 
are  similar  to  those  pertaining  to  the  electrolysis  of 
salts  in  solution.  A  certain  amount  of  current  passed 
through  the  fused  salt  will  always  produce  a  certain 
amount  of  decomposition  and  it  is  therefore  possible 
to  calculate  the  amount  of  energy  required  to  separate 
a  definite  weight  of  a  compound  into  its  elements. 
When  an  anhydrous  salt  is  used  as  an  electrolyte  a 
red  heat  is  usually  required  to  bring  it  to  a  fluid  con- 
dition and  its  electrolysis  is  a  furnace  operation.  Elec- 
trolytic processes  may  be  intended  either  for  purifica- 
tion or  the  recovery  of  metals. 

Chlorine  and  caustic  soda  are  made  by  the  use  of 
common  salt  as  an  electrolyte,  carbon  as  the  anode 
electrode,  and  molten  lead  as  the  cathode.  The  clorine 
collected  at  the  anode  is  used  for  making  bleaching 
powder,  and  the  sodium  liberated  at  the  cathode  alloys 
with  the  lead,  and  when  treated  with  steam,  combines 
to  form  caustic  soda. 

Metallic  sodium  is  usually  made  by  using  the 
fused  anhydrous  caustic  soda  as  an  electrolyte  with  a 
nickel  anode  and  a  carbon  or  metallic  cathode.  (Casner 
Process).  Other  processes  for  producing  sodium 
direct  from  salt  have  been  attempted  with  some  suc^ 
cess. 

Potassium  is  obtained  by  electrolytic  processes 
similar  to  the  sodium  processes. 


ELECTRIC     FURNACE     APPLICATIONS  161 

Barium,  magnesium,  strontium,  and  calcium,  are 
obtained  by  electrolysis  of  the  fused  chlorides. 

A  method  of  treating  various  sulphide  ores  has 
been  tried  out  with  some  success.  It  is  done  by  de- 
composing the  fused  ores  of  such  metals  as  lead,  iron 
and  zinc  by  the  action  of  chlorine. 

Zinc  may  be  obtained  from  the  fused  chloride.  The 
furnaces  employed  are  usually  provided  with  carbon 
anodes  and  zinc  cathodes. 

Production  of  Aluminum.  The  most  important 
metal  that  can  be  commercially  produced  solely  with 
electricity  in  the  electrolytic  furnace,  is  aluminum.  It 
was  originally  produced  in  very  small  quantities  by 
complicated  chemical  methods.  Prior  to  the  expira- 
tion of  the  Hall  patents  the  manufacture  of  aluminum 
in  the  United  States  was  controlled  by  the  Aluminum 
Company  of  America,  but  since  that  time  other  finan- 
cial interests  have  taken  up  its  production.  Nearly  a 
hundred  thousand  horsepower  of  electric  energy  is 
in  use  for  this  purpose  in  the  United  States,  although 
the  largest  percentage  of  the  world's  output  is  now 
manufactured  in  Europe. 

The  process  consists  in  passing  current  through 
melted  aluminum  compounds.  The  electrolytic  action 
liberates  the  aluminum  from  the  fused  compounds  and 
splits  up  the  aluminajnto  oxygen  and  aluminum.  The 
types  of  furnaces  most  generally  used  consist  of  car- 
bon lined  tanks  provided  with  carbon  electrodes  which 
extend  from  the  top  and  dip  into  the  fused  electrolyte. 
Direct  current  only  can  be  used  in  this  process.  The 
carbon  electrodes  are  made  the  positive  and  the  tank 
the  negative  terminals. 

Electrolytic  Furnace  Refining. — Although  it  is  en- 
tirely feasible  to  refine  metals  in  the  electrolytic  fur- 
nace, the  method  has  not  been  generally  employed  on 
account  of  the  expense  and  difficulty  of  high  tempera- 
ture operation.  The  principles  involved  are  similar 
to  those  of  refining  in  aqueous  solutions.  The  metal 
to  be  refined  is  made  the  anode  and  some  fused  salt  of 
the  metal  is  used  as  an  electrolyte.    Upon  the  passage 


162  ELECTRIC     HEATING 

of  current  through  the  furnace  the  pure  metal  is  de- 
posited upon  the  cathode. 

Production  of  Nitric  Acid  and  Nitrates. — The  prin- 
ciple on  which  furnaces  for  this  work  are  designed  is 
the  forcing  of  air  through  an  enormous  arc  and  remov- 
ing and  cooling  the  air  quickly.  The  oxygen  and 
nitrogen  of  the  air  partly  combine  to  form  a  very 
small  amount  of  nitric  oxide,  the  percentage  varying 
with  the  temperature.  The  nitric  oxide,  while  cooling, 
combines  with  oxygen  to  form  various  oxides  of 
nitrogen. 

After  the  gases  have  cooled  they  are  allowed  to 
react  with  water  in  spraying  towers,  forming  nitrous 
and  nitric  acid.  The  former  decomposes  into  nitric 
acid  and  nitric  oxide.  The  nitric  acid  may  be  marketed, 
or  it  may  be  utilized  for  dissolving  limestone  and  pro- 
ducing calcium  nitrate  which  is  useful  for  fertilizer. 

Three-phase  alternating  current  is  generally  used 
in  the  main  circuit  of  the  furnaces  now  in  operation 
and,  in  order  to  maintain  a  steady  arc,  resistance  or 
inductance  coils  are  connected  in  series  with  it.  The 
latter  wastes  less  energy,  but  necessarily  reduces  the 
power  factor  of  the  apparatus.  Pressures  as  high  as 
5000  volts  are  often  used.  A  magnetic  field  produced 
by  a  direct  current  electro-magnet  supplied  with  en- 
ergy from  some  auxiliary  source  is  often  employed  to 
direct  the  arc  upward  or  downward. 

Many  thousands  of  horsepower  are  utilized  in  the 
fixation  of  atmospheric  nitrogen  by  electric  furnace 
methods,  and  as  the  demand  for  nitrates  is  rapidly  in- 
creasing, the  industry  gives  promise  of  a  healthy 
growth. 

Miscellaneous  Electric  Furnace  Products. — Glass 
may  be  melted  to  advantage  in  the  electric  furnace. 
Alundum,  which  is  used  as  an  abrasive,  may  be  made 
by  fusing  bauxite  in  an  electric  \furnace  and  cooling 
slowly.  Quartz  used  for  making  laboratory  crucibles, 
dishes,  tubes,  etc.,  may  be  fused  in  the  electric  furnace. 
The  production  of  phosphorus,  which  can  only  be  han- 
dled away  from  the  air,  is  readily  made  in  the  electric 
furnace  by  heating  mineral   phosphates   or  bone   ash 


ELECTRIC     FURNACE     APPLICATIONS 


163 


with  carbon  and  silica.  Monox,  a  substance  used  in 
inks  and  paints,  is  produced  in  the  electric  furnace 
from  silicon  and  oxygen.  Carbon-bisulphide,  made  by 
passing  sulphur  vapor  over  hot  charcoal,  is  a  liquid 
used  as  a  solvent  for  oil  and  rubber,  and  being  volatile, 
it  is  sometimes  employed  for  producing  poisonous 
gases. 

Production  of  Electric  Furnace  Steel. — The  use  of 

electricity  in  melting  and  refining  steel  is  entering 
upon  a  period  of  rapid  growth.  The  development  of 
commercial  apparatus  has  passed  beyond  the  experi- 
mental stage  as  proven  by  the  fact  that  there  are  now 
over  three  hundred  such  furnaces  in  actual  service, 
about  seventy  of  which  are  located  in  various  parts  of 
the  United  States.  Since  there  are  between  thirty 
and  forty  million  tons  of  steel  produced  annually  in 
this  country  by  fuel  methods,  the  opportunity  for  intro- 
ducing electric  furnaces  is  great. 

Advantages  of  Electric  Steel  Furnace. — As  far  as 
cost  is  concerned,  it  is  unquestionably  cheaper  to  pro- 
duce the  highest  quality  steel  in  the  electric  furnace. 
For  large  quantity  production  of  the  lower  grades  of 


Rennerfelt   Steel  Arc  Furnace. 


164  ELECTRIC     HEATING 

steel,  it  is  sometimes  possible  to  make  the  steel  cheaper 
by  fuel  methods.  For  small  quantity  production  the 
cost  is  always  in  favor  of  the  electric  furnace.  This 
situation  opens  up  a  wide  field  for  relatively  small 
furnaces  having  a  capacity  for  fifty  tons  per  day  or 
less,  although  they  may  be  obtained  in  any  size  or 
capacity  desired. 

Electric  furnace  steel  may  be  made  to  any  anal- 
ysis or  specifications.  Purity  of  steel  is  a  mark  of 
quality  and  it  is  now  recognized  that  electric  furnace 
steel  is  the  purest  that  can  be  produced.  Among  the 
many  superior  qualities  claimed  for  electric  furnace 
steel  are  toughness,  greater  tensile  strength,  higher 
elastic  ratio,  more  solidity  and  fewer  blow  holes, 
higher  magnetic  properties,  and  greater  malleability. 
It  is  coming  into  great  demand  for  large  castings 
where  quality  is  the  first  consideration.  One  great 
advantage  of  the  electric  furnace  in  the  refining  of 
steel  is  that  electricity,  unlike  fuel,  introduces  no  addi- 
tional impurities  into  the  molten  metal,  and  a  com- 
plete charge  may  be  left  in  the  furnace  as  long  as 
desired  without  injuring  its  composition.  Impurities, 
such  as  sulphur,  phosphorus,  oxygen,  etc.,  are  grad- 
ually absorbed  in  the  slag  and  rabbled  oflf. 

Electric  Steel  Smelting. — Steel  may  be  produced 
directly  by  smelting  iron  ore  or  indirectly  from 
wrought-iron  or  pig  iron.  Whereas  the  former  method 
is  more  complicated  and  has  not  yet  been  taken  up 
commercially,  it  has  big  possibilities.  The  reduction 
of  the  ore  is  usually  done  in  the  furnace  shaft,  and 
the  refining  in  an  open  hearth  or  ladle. 

Production  of  Steel  from  Metals. — The  electrical 
method  of  making  steel  from  metallic  ingredients, 
known  as  the  indirect  method,  has  proved  to  be  en- 
tirely practical  commercially  and  is  being  rapidly 
adopted.  Pig  iron,  wrought  iron,  scrap  steel,  or  mild 
steel,  are  melted  together  in  this  process  and  refined 
to  whatever  extent  is  considered  necessary. 

Resistance  Furnaces. — Resistance,  induction,  and 
arc  furnaces  are  each  used  in  the  steel-making  indus- 
try.    Resistance  type  furnaces,  notably  the  Gin  Steel 


I 


ELECTRIC     FURNACE     APPLICATIONS  165 

Furnaces,  are  heated  by  passing  a  heavy  current 
through  the  charge  under  low  voltage.  The  charge 
is  placed  in  narrow  winding  channels  and  the  current 
introduced  at  each  end  through  water  cooled  elec- 
trodes. This  type  of  furnace  has  not  proven  altogether 
satisfactory-  in  actual  service,  and  later  designs  pro- 
vide for  heating  the  charge  on  the  induction  principle. 

Induction  Furnaces. — Heat  is  produced  in  these 
furnaces  by  inducing  a  current  in  the  charge  placed 
in  one  or  more  annular  rings  which  act  as  transformer 
secondaries.  A  great  m.any  advantages  are  claimed 
for  this  type  of  furnace.  In  the  first  place,  no  elec- 
trodes are  required  and  all  the  difficulties  and  expense 
which  attend  their  use  are  eliminated.  The  loss  of 
heat  by  conduction  to  the  outside  through  the  elec- 
trodes is  obviated.  There  are  no  electrode  impurities 
introduced.  The  steel  is  contained  in  a  closed  recep- 
tacle resembling  the  crucible  furnace.  The  distribu- 
tion of  heat  is  uniform  and  the  natural  circulation  set 
up  serves  to  mix  the  charge.  The  heat  of  the  furnace 
walls  and  cover  is  less  intense  than  in  the  arc  fur- 
nace and  the  lining  does  not  wear  away  so  rapidly. 
Although  this  type  of  furnace  may  create  a  relatively 
low  power  factor,  it  is  much  less  subject  to  extreme 
variations  in  load  than  are  arc  furnaces. 

The  efficiency  of  electric  transformation  in  this 
type  of  furnace  is  not  high.  It  is  necessarily  somewhat 
limited  in  capacity  because  the  power  factor  becomes 
less  as  the  size  is  increased  unless  the  frequency  of 
the  current  is  correspondingly  reduced.  Pressures  as 
high  as  6000  volts  may,  however,  be  applied  directly  to 
the  furnace,  thus  obviating  the  necessity  of  providing 
special  transformers,  unless  the  power  is  to  be  trans- 
mitted a  considerable  distance. 

Types  of  Induction  Furnaces. — The  Kjellin  fur- 
nace is  of  the  single-phase  type,  and  consists  essential- 
ly of  an  iron  core  around  one  leg  of  which  is  wound 
a  primary  winding,  enclosed  in  a  refractory  core  and 
cooled  by  forced  draft  or  water  jackets.  The  hearth 
surrounding  the  coil  is  provided  with  an  annular 
groove  in  which  the  charge  is  placed.     The  furnace  is 


166  ELECTRIC     HEATING 

usually  built  in  a  circular  iron  casing  which  is  lined 
with  firebrick.  The  annular  troug-h  is  surrounded  with  a 
more  refractory  material  such  as  dolomite  or  magnesite 
bricks. 

The  Colby  furnace  is  similar  in  principle  to  the 
Kjellin  furnace.  It  consists  of  a  laminated  iron  core 
around  which  is  wound  a  copper  tube  primary  cooled 
by  circulating  water.  The  annular  crucible  secondary 
surrounds  the  primary  winding.  It  is  claimed  that  this 
design  operates  at  a  much  higher  power  factor.  The 
character  of  the  primary  winding  requires  the  use  of 
lower  potentials.  It  has  proved  successful  in  small 
designs  but  has  not  as  yet  been  developed  in  large 
sizes.  The  Frick  furnace  resembles  the  Kjellin  fur- 
nace, but  is  generally  designed  for  two-phase  opera- 
tion. 

The  Rochling-Rodenhauser  furnace  is  so  designed 
as  to  obviate  two  of  the  most  objectionable  features 
of  other  induction  furnaces.  It  is  provided  with  a  dis- 
tinct open  hearth  so  that  refining  possess  may  be 
carried  on  in  the  furnace,  and  is  designed  to  operate 
in  larger  sizes  and  at  higher  power  factors.  This  fur- 
nace is  built  for  either  single  or  three-phase  operation. 
In  the  single-phase  type  two  annular  troughs,  sur- 
rounding two  separate  sections  of  the  primary  coil  meet 
in  the  center  of  the  furnace  and  are  there  expanded 
into  a  much  larger  chamber.  The  three-phase  type  is 
provided  with  three  annular  troughs,  surrounding 
three  separate  single-phase  windings.  These  troughs 
also  converge  in  the  center  into  a  much  larger  cham- 
ber. 

In  order  to  maintain  the  heat  in  the  enlarged 
chamber  a  separate  secondary  winding,  of  a  few  turns 
of  heavy  conductor,  is  connected  with  iron  pole  pieces 
imbedded  in  the  furnace  walls  at  opposite  sides  of  the 
chamber.  When  the  furnace  walls  heat  up  they  con- 
duct current  from  these  pole  pieces  through  the  charge, 
and  thus  form  a  closed  circuit  for  the  induced  cur- 
rents and  an  auxiliary  means  of  heating  the  charge 
in  the  chamber.  This  winding  also  serves  to  neutral- 
ize the  great  self-induction  produced  by  the  charge, 


ELECTRIC     FURNACE     APPLICATIONS 


167 


and  a  far  better  power  factor  is  obtained  than  in  the 
Kjellin  furnace.  The  use  of  three-phase  types  has  the 
advantag-e  of  causinj^  a  circulation  of  the  charge  due 


I 


UiK'hling^-Rodenhauser  2-Ton  Induction  Furnace. 

to  the  rotary  magnetic  field  set  up  and  results  in  a 
more  uniform  product.  Both  single  and  three-phase 
types  are  provided  with  lateral  doors  and  arranged  for 
tilting  to  pour  steel  and  slag. 

Arc  Furnaces. — The  usual  classification  of  steel 
arc  furnaces  are  (1)  independent  arc,  (2)  direct  heat- 
ing arc,  and  (3)  direct  heating  series  arc.  There  are  a 
number  of  advantages  of  the  arc  furnace  over  the  in- 
duction furnace  in  steel  making.  They  may  be  started 
with  a  cold  charge  more  readily.     There  is,  however, 


168 


ELECTRIC     HEATING 


considerable  loss  of  heat  which  is  conducted  to  the 
outside  through  the  electrodes.  The  slag  is  obviously 
heated  hotter  than  the  metal  and  as  the  impurities  are 
absorbed  in  the  hottest  portion  of  the  charge  the  arc 
furnace  is  well  adpated  to  refining  purposes.  These 
furnaces  are  also  less  complicated  in  design  and  have 
a  lower  first  cost.  The  power  factor  of  the  load  is 
much  higher  than  that  produced  by  the  induction 
furnace,  and  the  necessity  of  utilizing  special  fre- 
quencies in  the  larger  sizes  is  less  marked.  The  load  is, 
however,  subject  to  wide  variations,  especially  in  the 
direct  heating  are  furnaces  when  cold  scrap  is  melting 
down  or  flux  is  thrown  into  the  chamber.  Either 
direct  or  alternating  current  may  be  used  in  the  arc 
furnace. 

Under  average  commercial  conditions  arc  fur- 
naces show  better  cost  results  in  heating  cold  metal 
than  in  heating  molten  iron  from  a  fuel  furnace.  Com- 
bustion melting  introduces  impurities  from  the  metal, 
oxygen  and  nitrogen  from  the  blast,  and  sulphur  from 
the  fuel. 


Electrode  and  Connections  of  the  Rennerfelt  Arc  Furnace. 


ELECTRIC     FURNACE     APPLICATIONS 


169 


Independent  Arc  Furnaces. — Heat  is  produced  by 
one  or  more  arcs  above  the  charge  in  a  refractory 
chamber  in  this  type  of  furnace  and  the  steel  is 'heated 
by  radiation  from  the  arc.  The  Stassano  steel  making 
furnace  is  an  example  of  this  class.  It  usually  con- 
sists of  a  chamber  lined  with  magnesia  blocks  and 
three  electrodes  supported  from  the  sides  at  an  angle 
of  about  15°  with  the  horizontal.  It  is  mounted  on 
trunnions  and  may  be  tilted  for  skimming  the  slag 
or  pouring  the  metal.  The  length  of  the  arcs  drawn 
may  be  regulated  at  will  and  movements  of  the  charge 
do  not  vary  the  load.  It  is  said  that  the  load  is  almost 
non-inductive  and  very  steady. 


End   View   of   a    12-Ton    Rennerfelt    Furnace. 


Types  of  Independent  Arc  Furnaces. — The  Stas- 
sano furnace  in  types  similar  to  that  described  above 
was   the   forerunner   of   the    Rennerfelt.    The    former 


170 


ELECTRIC     HEATING 


Started  with  a  radiating  arc,  playing  almost  horizon- 
tally over  the  bath,  whereas  the  latter  furnace  forces 
the  flame  down  on  the  charge  by  employing  a  special 
electrode  arrangement. 

Polyphase  current  of  any  frequency  or  voltage 
may  be  used  but  three-phase  current  is  generally  sup- 
plied to  the  transformers  and  changed  by  means  of 
the  Scott  connection  to  two-phase  three-wire  current 
at  70  to  110  volts.  One  electrode  enters  centrally 
through  the  roof  and  two  horizontally  through  the 
sides.  The  diameters  of  the  electrodes  varies  from 
1^  in.  for  the  small  sizes  up  to  4  or  5  in.  for  the  large 
sizes.  The  middle  or  combined  electrode  carries  about 
40  per  cent  more  current  than  either  of  the  side  elec- 


W  i^  ^i^'xhf^ 


Side  View  of  a  12-Ton  Rennerfelt  Furnace, 


trodes.  If  direct  current  is  used  the  horizontal  elec- 
trodes are  coupled  in  parallel,  whereas  the  vertical 
electrode  is  connected  with  the  other  pole. 


ELECTRIC     FURNACE     APPLICATIONS  171 

The  furnace  is  generally  built  with  a  horizontal 
cylindrical  steel  shell,  supported  on  rollers  or  trun- 
nions with  one  charging  and  casting  door  on  the  side 
or  in  the  end  of  the  furnace.  The  shell  is  lined  with 
asbestos  board,  next  to  which  firebricks  are  built  in 
rings.  An  acid  or  basic  lining  is  then  placed  over  the 
firebricks. 

The  electrodes  in  the  smaller  furnaces  are  man- 
ually operated,  whereas  they  are  automatically  regu- 
lated in  the  larger  types.  It  is  not  necessary  to  adjust 
the  horizontal  electrodes  during  the  furnace  operation. 

Direct  Heating  Arc  Furnace. — The  charge  forms 
one  pole  of  the  circuit  in  this  type  of  furnace  and  is 
thus  heated  directly  as  well  as  by  radiation.  The  sim- 
plest types  consist  of  an  enclosed  chamber  lined  with 
refractory  material  and  provided  with  two  electrodes, 
one  at  the  top  which  is  adjustable  and  one  which  is 
fixed  in  contact  with  the  charge  at  the  bottom.  The 
arc  is  made  to  play  between  the  upper  electrode  and 
the  charge. 

Types  of  Direct  Heating  Arc  Furnaces. — The 
Girod  furnace  is  a  typical  example  of  the  direct  heat- 
ing arc  furnace.  It  is  provided  with  one  or  more  ad- 
justable carbon  electrodes  of  one  polarity  supported 
from  the  top.  The  lower  electrodes  are  made  up  of  a 
number  of  iron  or  steel  bars  passing  through  the  bot- 
tom of  the  furnace  and  making  contact  with  the  charge. 
The  casing  is  of  iron  or  steel  lined  with  magnesite  or 
dolomite.  The  cover  is  lined  with  silica  bricks  and 
may  l)e  lifted  ofif.  The  furnace  is  made  round,  or 
square  with  rounded  corners.  It  is  easily  operated, 
and  the  electric  current,  which  passes  through  the  en- 
tire charge,  makes  it  heat  quickly  when  started  cold. 

The  Keller  steel  furnace  is  similar  in  principle  to 
the  Girod  furnace,  although  dififering  somewhat  in 
design. 

The  *'Electro-Metals"  steel  furnace  is  usually  de- 
signed for  two-phase  operation.  It  is  provided  with 
two  adjustable  carbon  electrodes  which  enter  through 
the  roof.  A  permanent  carbon  electrode  in  contact 
with  the  metallic  shell  is  built  into  the  bottom  of  the 


172 


ELECTRIC     HEATING 


furnace.  The  magnesite  lining  covers  the  bottom 
electrode  completely.  One  phase  is  connected  to  each 
top  electrode,  and  the  other  pole  of  each  phase  is  con- 
nected to  the  bottom  electrode.  When  the  furnace  is 
started  cold,  current  passes  between  the  two  upper 
electrodes  through  the  metallic  charge.  As  soon  as 
the  lining  is  heated  it  begins  to  conduct  current  from 
the  bottom  electrode  through  the  charge  to  each  top 
electrode.  This  furnace  will  operate  more  steadily 
than  the  Girod  or  Keller  because  if  one  arc  is  broken 
the  whole  supply  of  energy  is  not  cut  oflf. 

The  Snyder  steel  furnace    is    of   the    single    elec- 
trode direct  heating  arc  type  and  has  met  with  con- 


.,:« 

li— 

i 

— Jt  - 

Snyder   Steel    Furnace. 


LOW     TEMPERATURE     FURNACES  173 

siderable  favor.  There  are  about  15  of  these  furnaces 
in  use  in  the  United  States  and  Canada  at  the  present 
time,  varying  in  capacity  from  6  to  30  tons  of  steel 
castings  per  24  hours.  Several  furnaces  are  being  used 
for  smelting  ferrosilicon,  one  for  melting  brass  and 
seven  for  special  chemical  work. 

Series  Arc  Furnaces. — As  the  name  implies  the 
direct  heating  series  arc  furnace  has  two  or  more  arcs 
in  series.  The  current  passes  from  one  electrode 
through  an  arc  to  the  charge  and  from  the  charge 
through  another  arc  to  another  electrode.  The  hearth 
is  usually  made  of  burnt  magnesite  or  similar  material. 

Types  of  Series  Arc  Furnaces. — The  Heroult  is 
the  best  known  example  of  a  series  arc  steel  furnace. 
It  has  made  the  most  favorable  impression  in  this 
country,  as  evidenced  by  the  fact  that  there  are  now 
about  forty  in  use  in  the  United  States.  It  is  usually 
lined  with  dolomite  brick  next  to  the  casing  with  an 
interior  lining  of  crushed  dolomite.  The  roof  is  made 
of  silica  brick  covered  on  the  outside  with  a  steel 
casing.  The  two  electrodes  are  cooled  with  water 
jackets,  and  are  each  automatically  adjusted  by  the 
variation  of  the  furnace  voltage. 

The  operation  of  a  five-ton  Heroult  furnace  is. 
shown  in  some  data  prepared  by  Professor  Eichhoff  of 
Charlottenburg: 


Generator  Capacity. 

Condition  of  Charge. 

Length  of  Heat. 

Kw 

-hr.  per  ton 

750  kw. 

Cold 

6.05   hr. 

725 

750   kw. 

Cold 

6.63   hr. 

795 

750   kw. 

Cold. 

7.22  hr. 

868 

643   kw. 

Hot 

2.57   hr. 

265 

64r;   kw. 

Hot 

v.. 17)  hi-. 

:J24 

The  Keller  furnace  is  another  type  of  series  arc 
direct  heating  furnace.  It  is  provided  with  four  car- 
l^on  electrodes  and  may  be  used  for  single,  two  (jt 
three-phase  operation. 


isuv 


CHAPTEK    XII 

LOW  TEMPERATURE  ELECTRIC   FURNACES 
AND  OVENS. 

Field  of  Application. — Aside  from  the  electric  fur- 
naces used  in  electrochemical  and  electro-metallurgical 
processes  there  are  many  other  electric  oven  and  fur- 
nace applications  designed  for  industrial  heating  oper- 
ations which  require  relatively  high,  moderate,  or  low 
temperatures.  The  possibilities  for  applying  electric 
heat  in  this  manner  are  so  many  and  varied  that  only 
a  small  percentage  of  them  will  be  considered.  The 
various  processes  will  be  classified  with  reference  to 
their  temperature  requirements  and  to  the  kind  of 
work  which   they   are   intended   to   accomplish. 

Advantages  of  Electric  Operation. — The  points 
of  superiority  of  electric  furnaces  to  fuel  furnaces 
are  numerous  and  vary  considerably  with  the  char- 
acter of  the  work  to  be  performed.  Some  of  the  ob- 
vious advantages  are  the  elimination  of  fire  and  ex- 
plosion hazards.  The  danger  of  overheating  or  burn- 
ing the  charge  is  also  removed.  For  tempering,  forg- 
ing, hardening,  annealing,  etc.,  the  uniform  heat  ob- 
tainable is  ideal.  The  reduction  in  scale  formation 
during  the  heating  of  tools,  saves  the  metals  and  in- 
sures a  better  finished  product.  Unlike  fuel  equip- 
ment, the  electric  furnace  gives  ofif  little  heat  to  the 
surrounding  atmosphere  and  the  working  conditions 
are  therefore  far  more  satisfactory  in  hot  weather. 

Furnace  Processes. — Resistance  furnaces  may  be 
used  for  vitreous  enameling,  for  heating  bolt  and  rivet 
stock,  for  welding  and  forging  steel  parts,  for  harden- 
ing high  speed  steel,  and  for  melting  such  metals  as 
copper  and  gold.  The  temperatures  required  for  this 
work  may  vary  from  1800°  to  2500°  F.    Furnaces  oper- 


LOW  TEMPERATURE  FURNACES       175 

ating  at  temperatures  from  850°  F.  to  1800°  F.  are 
often  used  for  (1)  case  hardening,  (2)  annealing  brass, 
copper,  malleable  iron,  carbon  steel  and  high  speed 
steel,  (3)  hardening  some  high  speed  steels,  and  car- 
bon steel,  (4)  melting  aluminum,  silver,  zinc,  etc. 
Temperatures  varying  from  500°  F.  to  850°  F.  are  often 
employed  for  boiling  varnishes,  heating  oil  tempering 
baths,  sherardizing,  some  forms  of  annealing,  and  for 


General    Electric    Type    RHF    25    kw.    Hardening 
Furnace  Outfit. 

melting  lead,  tin,  babbitt,  etc.  Temperatures  of  from 
200°  F.  to  500°  F.  are  utilized  for  heating  cores,  vul- 
canizing, drying  impregnated  woods,  and  baking 
enamels,  lacquers,  japans,  insulating  compounds,  etc. 
Lower  temperatures  may  be  employed  for  various 
drying  purposes,  bacteriological  processes,  incubation, 
etc. 

Carbon-Resistance  Type  Furnaces. — For  tempera- 
tures ranged  from  850°  F.  to  2500°  F.  this  type  of 
furnace  is  often  used.  The  walls  are  usually  con- 
structed of  fire  brick  supported  on  iron  framework. 
The  heating  chamber  is  lined  with  refractory  material 
and  equipped  with  a  main  and  an  auxiliary  resistor. 
Powdered  coke  is  the  main  resistor  and  is  laid  to  a 


176  ELECTRIC     HEATING 

depth  of  several  inches  upon  the  furnace  floor.  The 
roof  is  the  auxihary  resistor.  It  is  made  of  special 
refractory  material  that  becomes  an  electrical  con- 
ductor when  heated  to  a  high  temperature.  Both 
the  main  and  auxiliary  resistors  are  in  contact  with  the 
carbon  electrodes  at  opposite  sides  of  the  furnace.  By 
controlling  the  ventilation  in  this  type  of  oven  an  oxi- 
dizing, neutral,  or  reducing  atmosphere  may  be  secured. 
If  the  ventilation  is  cut  off,  the  oxygen  in  the  air  com- 
bines with  the  carbon.  Neutral  and  reducing  tem- 
peratures are  essential  in  the  treating  of  various  metals 
and  the  value  of  electric  operation  is  therefore  ap- 
parent. These  furnaces  are  usually  controlled  by  ther- 
mostatic devices  which  operate  relays  and  switches 
mounted  on  main  control  panels. 

Another  type  of  carbon  resistance  furnace  consists 
of  two  piles  of  flat  carbon  plates  on  opposite  sides  of 
the  furnace.  The  two  sets  of  resistors  are  usually  con- 
nected together  at  the  top  and  current  introduced  at 
the  two  lower  ends  by  means  of  heavy  carbon  elec- 
trodes. Heat  is  generated  by  the  resistance  which  the 
carbon  plates  offer  to  the  flow  of  electric  current.  The 
Hoskins  Company  manufactures  small  crucible,  muffle, 
and  drill  furnaces  of  this  type.  It  also  makes  car- 
bon resistance  tube  furnaces  using  carbon  rings  to 
which  energy  is  supplied  from  opposite  ends  of  the 
tubes. 

Metallic  Resistance  Type  Furnaces. — For  produc- 
ing any  desired  temperature  up  to  1800°  F.  the  heat- 
ing units  may  be  made  of  metallic  resistance  material. 
They  are  adaptable  to  all  kinds  and  classes  of  work 
where  a  clean,  dry,  uniform  heat  of  low  or  moderate 
temperature  is  required.  There  are  so  many  different 
designs  of  metallic  resistance  furnaces,  which  depend 
upon  the  class  of  work  for  which  they  are  to  be  used, 
that  only  a  few  will  be  described.  They  are  usually 
<:ontrolled  thermostatically.  The  heating  elements 
may  be  in  the  form  of  grids  or  coils  of  wire. 

Some  of  the  industrial  processes  that  may  be  per- 
formed with  electric  heat,  and  the  temperatures  re- 
quired are  given  in  the  accompanying  table  : 


LOW  TEMPERATURE  FURNACES       177 

Temperature 
Range. 

Process.  Deg.   F. 

Baking  of  japan 300-   600 

Baking  of  varnish  and  paints 100-   300 

Baking    color    enamels 100-   300 

Baking  foundry  core.s 350-   500 

Baking  insulations 200-   500 

Annealing  copper    350-   700 

Annealing  aluminum 500-   800 

Annealing  glass 900-1000 

Tempering  steel    200-1000 

Melting    lead     620-   700 

Melting  tin    450-   500 

Melting    babbitt     450-   700 

Wax  and  compounds   150-   500 

Heating  coils    100-1000 

Heating  metal    molds 200-1000 

Lumber   drying   kilns    100-   200 

Boiling    varnishes     150-   500 

Soldering     400-   650 

Glue  pots   100-   200 

Melting  type-metal,  linotype  machines 625-   700 

Sheradizing 650-   700 

Furnace  Selection. — In  order  to  select  the  proper 
type  of  furnace  for  any  kind  of  work  it  is  necessary 
to  know  the  temperature  to  which  the  material  is  to 
be  heated,  the  number  of  pounds  and  character  of  ma- 
terial to  be  treated,  the  weight  and  dimensions  of  each 
piece,  and  whether  the  material  is  to  be  melted,  forged, 
hardened,  tempered,  or  annealed. 

A  furnace  should  be  selected  of  the  proper  kilo- 
watt capacity  and  dimensions  for  the  work  in  hand. 
Its  thermal  efficiency  should  be  high,  and  it  should  be 
designed  as  nearly  as  possible  for  continuous  opera- 
tion at  its  maximum  capacity  in  order  to  insure  eco- 
nomic and  satisfactory  results. 

Enameling  Ovens. — The  extremely  rapid  progress 
that  has  recently  been  made  in  the  utilization  of  elec- 
tricity for  baking  enamels,  lacquers,  japans,  etc.,  has 
opened  up  a  very  wide  market  for  central  station 
power.  After  making  careful  preliminary  investiga- 
tions into  the  relative  merits  of  fuel  and  electric  enam- 
eling ovens  the  Overland  Automobile  Company  has  in- 
stalled 6000  kilowatts  capacity  in  enameling  ovens  hav- 
ing a  total  content  of  50,000  cubic  feet.  The  Ford 
Company  has  also  arranged  to  equip  a  large  number 
of  ovens  with  electric  heaters  at  its  main  factory  and 
at  its  various  assembling  works  throughout  the  coun- 
try. Both  concerns  have  remodeled  fuel  ovens,  instead 
of  waiting  to  build  new  electric  ovens,  which  is  con- 


178 


ELECTRIC     HEATING 


elusive  evidence  of  their  confidence  in  the  superiority 
of  electric  operation.  A  number  of  other  large  con- 
cerns are  arranging  to  take  similar  action. 


Japan    Baking   Oven. 


Advantages  of  Electric  Enameling  Ovens. — Elec- 
tricity supplies  a  clean,  dry  heat  that  is  under  posi- 
tive control  and  uniform  in  all  parts  of  the  oven.  The 
radiant  heat  drives  off  the  water  vapors,  produces  no 
additional  moisture,  and  gives  off  no  harmful  products 
of  combustion.  The  enamels  have  a  finer  finish,  and 
brighter  gloss,  are  of  better  quality,  and  can  be  turned 
out  with  greater  speed  than  with  any  type  of  fuel 
equipment.  The  hazard  from  fires  and  explosions  is 
also  reduced  by  electric  operation. 

In  baking  enamel  it  is  important  to  drive  off  the 
water  vapors  and  to  oxidize  the  enamel  film  in  order 


LOW     TEMPERATURE     FURNACES 


179 


to  secure  a  bright,  fine  finish.  Each  cubic  foot  of 
gas  burned  in  a  fuel  oven  throws  ofif  two  cubic  feet 
of  water  vapor  which  constantly  adds  to  the  moisture 
to  be  removed.  In  the  gas  oven  the  oxygen  of  the  air 
is  consumed  very  rapidly  thereby  retarding  the  oxida- 
tion of  the  enamel  film.  The  excessive  ventilation  re- 
quired in  the  gas  oven  to  remove  moisture  and  other 


Drying  and  Baking-  Oven  Loaded. 


products  of  combustion,  and  to  supply  sufficient  air 
for  the  proper  oxidation  of  the  enamel  film,  not  only 
carries  away  great  quantities  of  heat  but  picks  up  dust 
particles  from  the  outside  air  which  are  deposited  on 
the  soft  enamels. 

The  radiant  heat  supplied  by  the  electric  method 
is  distributed  uniformly  throughout  the  oven  whereas 
the  fuel  heat  is  likely  to  be  more  intense  at  the  top 


180 


ELECTRIC     HEATING 


than  at  the  bottom,  especially  when  rapid  ventilation 
has  to  be  provided.  The  danger  of  overbaking  is 
entirely  done  away  with  in  the  electric  apparatus.  The 
labor  cost  is  reduced,  and  the  ovens  being  thermostat- 
ically controlled,  no  watchmen  are  required  at  night. 
Steam  heat  cannot  be  used  for  high  temperature 
enameling  on  account  of  the  excessive  steam  pressures 
required.  In  order  to  attain  a  temperature  of  400°  F. 
for  instance,  a  steam  pressure  of  at  least  250  pounds 
is  necessarv. 


Combined  Steam  and  Electric  Japan  Baking-  Oven    (One 
compai'tment  being  loaded  and  the  other  baking). 


Greater  Production. — Electric  ovens  have  been 
found  capable  of  turning  out  from  40  per  cent  to  60 
per  cent  more  product  than  other  types.  Practically  all 
the  available  thermal  energy  is  directly  applied  to  use- 
ful work,  in  the  electric  oven.     It  may  be  operated  at 


LOW  TEMPERATURE  FURNACES       181 

very  nearly  the  limit  of  safe  operating  temperatures 
without  fear  of  destroying  the  product. 

Although,  in  some  cases,  the  total  cost  of  elec- 
tricity for  heating  an  oven  is  greater  than  where  fuel 
is  used,  the  improvement  of  the  work,  and  the  in- 
creased output,  usually  warrants  its  adoption. 

Characteristics  of  Enamels. — Different  grades  of 
enamel  are  required  for  different  classes  of  work. 
They  vary  in  their  analyses  and  in  their  baking  treat- 
ment. Some  harden  at  low  temperatures,  and  others 
will  stand  relatively  high  temperatures.  Some  ma- 
terial to  which  enamel  is  applied,  will  not  stand  high 
temperatures,  whereas  other  material  may  be  heated 


A    Set    of    Drying    and    Baking    Ovens. 

as  hot  as  the  enamel  will  permit.  Three  or  four  hours' 
application  of  heat  at  160°  F.  will  dry  Japans  that 
require  twenty-four  hours  or  more  to  harden.  En- 
amels that  will  bake  in  45  minutes  at  500°  F.  require 
from  four  to  five  hours  when  the  temperature  is  main- 
tained at  300°  F. 

The  greatest  economy  is  derived  from  the  use  of 
high  temperature  enamel.    By  bringing  up  the  temper- 


182  ELECTRIC     HEATING 

ature  rapidly,  and  doing  the  work  quickly,  convection 
and  radiation  losses  are  reduced. 

Equipping  Fuel  Ovens  for  Electric  Heat. — An  oil 
or  gas  fired  oven  may  be  fitted  with  electric  heaters 
by  replacing  the  burners  and  other  fixtures  with  elec- 
tric units.  If  the  old  oven  is  not  thoroughly  insulated 
against  heat  losses  it  should  be  reconstructed  to  insure 
satisfactory  operation.  The  ventilation  of  the  oven 
should  be  reduced,  and  arrangements  made  to  cut  it 
ofif  entirely  after  certain  temperatures  are  attained. 

There  are  several  kinds  of  enameling  ovens  de- 
signed for  electric  heat.  They  are  all  thoroughly  insu- 
lated against  heat  losses.  The  units  may  be  placed  on 
the  floor,  or  mounted  on  the  walls,  depending  upon  the 
size  of  the  oven,  and  the  shape  and  quantity  of  the 
work. 


-»»»        -in. 

"T^    I   Z^  ^j  ^ 

—    * 

■  rr:  ^      ^  :  r::     r:  "t 

11  il  11 

.-f    Si-^ 

UPE  St.     =s  «.,  me  %^ 

w^fJifiil.p 

'  ■           -    r      , 

General   Electric   400   Volt  Oven   Heating   Unit. 

Revolving  Type  Ovens. — In  this  type  of  oven  the 
work  is  pushed  into  the  oven  on  a  carriage,  and  while 
one  charge  is  baking  the  side  opposite  may  be  loaded. 
It  is  revolved  by  a  motor  attached  to  a  worm  gear. 
The  space  taken  up  by  this  type  of  oven  is  relatively 
small,  and  it  does  not  have  to  be  cooled  down  each 
time  a  charge  is  inserted. 

Drying  Ovens.  —  Electric  heat  has  been  suc- 
cessfully employed  for  drying  varnishes.     In  practice, 


LOW  TEMPERATURE  FURNACES       183 

ovens  varying  in  width  from  12  to  18  ft.,  and  in  length 
from  15  to  35  ft.,  are  usually  employed.  The  dryers 
are  designed  with  wood  or  iron  frame  works  covered 
with  fibre  board,  sheet  iron,  wood  and  asbestos,  in 
a  way  to  build  up  dead  air  spaces  and  retain  the  heat. 
Thermostatic  control  devices,  for  maintaining  uniform 
temperatures,  are  usually  provided. 

The  average  temperatures  required  inside  the 
dryers  for  securing  the  best  results  are  as  follows: 

Deg.   F. 

Varnishes  on   wood 110  to  125 

Varnishes  on  metal 110  to  130 

Stains    on    wood 100   to  125 

Fillers    on    wood .110   to   125 

Primers  on  wood 115  to  125 

Primers    on    metal 120   to   140 

Roug-h    stuff    on    metal 120   to   140 

Enam,els     on     metal 140  to   170 

The  maximum  temperatures  should  be  avoided 
unless  the  woods  are  free  from  moisture  and  easily 
softened  ingredients. 

The  periods  required  for  drying  various  coatings 
subjected  to  the  above  temperatures  are  approximately 
as  follows : 

Hours. 
2   and   3    day   varnishes   require 3      to    6 

4  and    5   day   varnishes   require 4      to    7 

5  and   6   day   varnishes    require 4      to    8 

7    and    8   day   varnishes   require 6i^tol0 

Fillers    require 4       to    6 

Water   stains   require 2      to    2^^ 

Rough    stuff    requires 2%  to    3% 

Primers    require 4      to    8 

The  most  desirable  humidity  to  maintain  during 
operation  varies  with  the  varnish  composition.  Some 
quick  drying  varnishes  require  no  artificially  produced 
moisture,  whereas  others  need  it  to  retard  surface  dry- 
ing. Premature  drying  often  interferes  with  the  evap- 
oration of  volatile  elements  and  the  necessary  penetra- 
tion of  oxygen  into  the  coating.  Simple  devices  for 
adding  moisture  to  the  air  may  be  obtained. 

Heat  Losses  Through  Oven  Walls. — Some  inter- 
esting tests  of  thermal  insulation  of  electric  ovens 
printed  in  the  Electrical  World  of  May  27,  1915,  page 
779,  aflford  information  of  considerable  value  to  the 
oven  designer.  The  apparatus  used  consisted  of  a 
specially  constructed  double  walled  oven  having  in- 


184  ELECTRIC     HEATING 

terior  dimensions  34^  in.  wide,  35^  in.  high  and  55j^ 
in.  long.  The  walls  were  made  of  half-inch  asbestos 
board,  calked  with  85  per  cent  magnesia  plaster,  with 
a  space  between  the  inner  and  outer  walls  of  approx- 
imately two  inches.  Six  kilowatts  capacity  in  heaters, 
arranged  for  a  wide  range  of  load,  were  installed  in 
the  inner  chamber.  Careful  tests  of  heat  losses  were 
made  under  the  following  conditions : 

(1)  With  the  outer  walls  removed. 

(2)  With  the  outer  walls  in  place,  leaving  an  air 
space  between  the  inner  and  outer  shells. 

(3)  With  three  wooden  strips  on  baffle  plates 
placed  horizontally  between  the  walls  around 
the  entire  oven  dividing  the  space  between 
the  shells  into  a  series  of  four  air  spaces. 

(4)  With  the  space  between  the  walls  packed 
with  cotton  waste. 

.  (5)  With  the  space  between  the  walls  packed 
with  mineral  wool. 
The  tests  of  course  indicated  the  greatest  losses 
with  the  outer  shell  removed.  The  use  of  the  outer  wall 
increased  the  efficiency  about  60  per  cent.  The  baffle 
plates  used  in  the  third  test  had  no  appreciable  effect. 
The  cotton  waste  improved  the  thermal  efficiency  near- 
ly 50  per  cent  and  the  mineral  wool  nearly  90  per  cent. 
A  summary  of  the  results  obtained  is  shown  in  the 
table. 

Thermal 
Resistance 
Test.  Nature    of    Wall.  Rating. 

1  S-ingle    shen 1 

2  Double   shell  and    simple   air    space 1.62 

3  Double   shell  and    cellular    air    space 1.62 

4  Double  shell  packed    with    cotton    waste 2.38 

5  Double  shell  packed    with    mineral    wool 3.07 


CHAPTER    XIII 

IXCUBATIXG  AND  BROODING. 


Modern  Methods. — Although  artificial  incubating 
and  brooding  has  been  practiced  for  many  years  in 
Europe,  Asia,  and  the  United  States,  the  latter  coun- 
try has  been  most  progressive  in  developing  means 
for  utilizing  electric  heat  as  a  substitute  for  heat  pro- 
duced by  fuel  combustion  methods.  The  superiority 
of  electricity  is  quite  obvious  to  anybody  familiar  with 
the  poultry  business.  The  number  of  fuel  heated  in- 
cubators  and   hovers   in   use   in   this   country   reaches 


Portion   of  White   Hatciiery,   Petaliima,   Cal. 
(Capacity  40,000  eggs.) 


186  ELECTRIC     HEATING 

well  into  the  millions,  but  the  vast  field  which  the 
application  of  electric  heat  to  these  devices  has  opened 
up  for  the  manufacturer  of  heating  apparatus  and  the 
distributor  of  electric  energy  is  little  appreciated.  In 
one  small  town  in  California  about  10,000,000  chicks 
are  hatched  annually  by  artificial  means.  The  hatch- 
ing and  brooding  of  these  chicks  would  require  about 
3,000,000  kw  -hr.  per  year,  if  electric  operation  was 
substituted  for  fuel. 

The  character  of  the  load  is  desirable  from  the 
standpoint  of  the  central  station.  The  machines  are 
non-inductive,  and  the  diversity  factor  is  naturally 
high.  Where  a  large  number  of  machines  are  in  use 
the  load  is  not  one  that  varies  greatly  with  the  season 
of  the  year  as  might  be  supposed. 

The  processes  of  incubating  and  brooding  are  out- 
lined in  order  to  convey  a  clearer  appreciation  of  the 
advantages  afforded  by  the  application  of  electric  heat. 

Poultry  Incubating. — All  kinds  of  eggs  may  be 
hatched  by  artificial  means.  The  period  of  incubation 
varies  with  the  kind  of  egg  and  with  temperature  con- 
ditions. If  the  heat  has  been  maintained  at  too  low  a 
temperature  during  the  period  of  incubation,  or  if  the 
eggs  have  been  chilled  or  overheated,  the  hatching 
may  be  delayed  somewhat. 

The  average  incubating  periods  of  various  kinds 
of  eggs  by  both  natural  and  artificial  methods  are  as 
follows : 

Days. 

Hen    egg 21 

Pheasant   egg- 23 

Guinea  egg 27 

Duck  egg 28 

Peafowl    egg 28 

Turkey    egg 28 

Goose  egg 32 

Duck  egg   (Muscovy)    34 

Ostrich  egg 42 

The  hatching  of  chickens  by  artificial  means  is 
perhaps  most  commonly  known,  and  is  therefore  de- 
scribed. 

Incubating  of  Chickens. — The  eggs  are  placed  on 
portable  trays  at  an  angle  of  about  45  degrees,  with 
the  small  ends  down,  leaving  the  air  cells  in  the  large 
ends.     These  trays  are  then  placed  in  the  incubator, 


INCUBATING     AND     BROODING 


187 


and  the  temperature  brought  up  gradually  to  102°  F., 
and  maintained  at  that  point  for  from  four  to  six 
days,  when  a  test  is  made.  This  test  consists  in  hold- 
ing the  tray  of  eggs  to  the  light.  If  they  are  fertile 
the  operator  will  observe  a  spider  like  shadow  within 
the  eggs,  showing  that  they  are  germinating.  The 
eggs  that  are  not  fertile  will  be  perfectly  clear,  and 
will  be  removed  from  the  tray.  Another  similar  test 
is  often  made  about  the  fourteenth  day.  After  the 
first  test  is  made,  the  temperature  is  usually  brought 


Petaluma  200  Egg  Incubator. 

Up  to  103°  F.  and  maintained  at  that  point  until  the 
hatch  is  off.  The  temperature  is  always  taken  with 
the  bulb  of  the  thermometer  even  with  the  horizontal 
plane  of  the  eggs. 

After  the  eggs  have  been  in  the  machine  about 
seventy-two  hours,  they  are  cooled  daily  by  removing 
the  trays  from  the  machine  for  from  one-half  hour  to 
two  hours,   depending  upon   the   temperature   of   the 


188 


ELECTRIC     HEATING 


incubating  room.  When  they  have  cooled  to  about 
the  temperature  of  one's  body,  (which  may  be  observed 
by  holding  one  of  them  against  the  cheek),  they  are 
put  back  in  the  machine.  The  eggs  are  cooled  to 
allow  the  germ  to  rest,  for  otherwise  the  chick  when 
hatched  would  be  weak  and  nervous.  Each  time  the 
eggs  are  cooled  they  are  turned  at  a  different  angle, 
but  the  small  end  is  always  kept  pointing  downward. 


Esco  100   Eg-g  Incubator. 


Constant  observations  are  made  to  see  that  the 
egg  is  drying  down  properly.  By  the  eighteenth  day  the 
air  cell  in  the  large  end  should  be  dried  down  to  about 
30  per  cent  of  the  total  volume  of  the  shell.  To  hasten 
the  drying  process,  ventilation  may  be  increased  pro- 
vided no  drafts  are  produced.  In  case  the  eggs  dry 
down  too  rapidly,  the  bottom  of  the  incubator  may 
be  sprinkled,  or  a  slight  spray  of  water  given  the  eggs. 

After  the  eighteenth  day  the  incubator  is  closed 
until  the  chicks  are  taken  off.  A  slight  film  of  moist- 
ture,  on  the  lower  edge  of  the  inside  glass,  usually 
indicates  that  the  air  is  of  proper  humidity  for  "pip- 
ping." As  the  chicks  "pip"  through  their  shells,  they 
drop  through  the  trays  to  the  space  below,  known  as 


INCUBATING     AND     BROODING 


189 


the  nursery.     After  they  are  about  twenty-four  hours 
old,  they  are  removed  to  the  brooders. 

Electric  Incubators. — These  appliances  usually 
consist  of  square  or  oblong  cases  mounted  on  wooden 
supports.  They  may  be  double  walled  with  shoddy, 
mineral  wool,  asbestos,  or  other  heat  insulating  ma- 
terial interposed,  or  single  walled  lined  with  heavy 
paper.  Tight  fitting  double  doors,  the  inner  one  always 
of  glass,  are  provided  along  the  front  for  examining 
the  interior  and  moving  the  egg  trays.  These  trays 
are  made  of  either  wood  or  metal  and  are  inserted  in 
the  machine  about  four  inches  from  the  bottom.  The 
heating  elements  are  usually  mounted  near  the  top 
of  the  egg  chamber,  although  in  some  makes  of  double 
deck  incubators  heating  elements  are  placed  near  the 
bottom,  as  well  as  at  the  top. 


Electro-Hatch   200   Egg  Incubator. 


Single  deck  types  are  claimed  to  be  more  satis- 
factory than  double  deck  machines,  on  account  of  the 
more  uniform  heat  that  may  be  applied  on  a  single 
plane.     On  the  other  hand,  the  double  deck  type  re- 


190 


ELECTRIC     HEATING 


quires  less  ener^i^y  for  heating  a  given  number  of  eggs. 
In  the  single  deck  types  provided  with  top  heating 
units,  the  temperature  is  naturally  higher  above  the 
eggs,  and  lower  below  them.  The  temperature  in  the 
nursery  below  the  trays  is  therefore  maintained  at 
about  95°  F.,  which  is  considered  most  desirable  for 
newly  hatched  chicks. 

The  thermometers  used  in  incubator  work  should 
be  high  grade  instruments,  because  it  is  essential  to 
know  at  all  times  just  what  temperatures  are  being 


i«^^^'i 


Esco  200  Kgg  Incubator. 


maintained.  A  slight  error  in  the  thermometer  will 
have  a  large  influence  on  the  success  of  the  hatch. 

Most  of  the  thermostats  that  have  been  developed 
for  use  with  electric  incubators  are  extremely  sensi- 
tive and  are  capable  of  maintaining  the  desired  temper- 
ature to  within  y4°  F.  to  ^°  F.  These  devices  should 
be  simple  in  construction,  positive  in  action,  and  abso- 
lutely reliable,  in  order  to  insure  the  best  results. 

A  well  constructed  single  deck  machine  is  gener- 
ally provided  with  an  average  of  about  75  watts  heat- 
ing capacity  per  100  eggs.  The  average  current  con- 
sumption has  been  found  to  be  about   10  kw  -hr  per 


INCUBATING     AND     BROODING  191 

hundred  chicks  hatched.    Incubators  are  now  available 
that  will  hold  from  30  to  1200  eggs. 

Advantages  of  Electric  Incubators. — An  incubator 
heated  by  coal,  oil,  or  gas  is  constantly  filling  the  ma- 
chine with  fumes  and  burning  up  oxygen  so  essential 
to  the  germ  life  in  the  egg,  whereas  electricity  neither 
destroys  good  air  nor  gives  off  bad  air.  The  tempera- 
ture control  is  simple  and  requires  no  attention,  other 
than  setting  the  thermostat  by  turning  a  thumb  screw 
a  couple  of  times  during  the  hatch.  The  fire  risk  is 
entirely  eliminated.  The  .anxiety  that  attends  the 
operation  of  fuel  heated  machines  is  done  away  with. 
The  distribution  of  heat  is  perfect  and  the  ventilation 
can  be  regulated  at  will.  Much  time  and  labor  usually 
required  in  looking  after  fuel  equipment  is  saved.  The 
machines  may  be  located  in  any  convenient  place  and 
are  adaptable  to  any  climate.  It  is  furthermore  inter- 
esting to  note  that  electrically  hatched  chicks  always 
begin  to  pip  about  twelve  hours  quicker  than  those 
hatched  by  other  artificial  means.  They  are  always 
stron^-er  and  more  vigorous,  and  statistics  show  that 
a  much  higher  percentage  is  hatched. 

Relative  Operating  Costs. — The  following  com- 
para':ive  figures  are  taken  from  many  averages  secured 
in  actual  practice.  They  are  based  on  an  assumed  in- 
cubator room  temperature  of  60°  F.  Although  a  rather 
low  rate  for  electricity  is  required  to  make  the  actual 
operating  cost  comparable  with  those  of  some  of  the 
less  expensive  fuels,  the  savings  effected,  the  better 
results  secured,  and  the  greater  degree  of  satisfaction 
obtained  by  electric  operation,  will  usually  overcome 
whatever  objection  arises  as  to  the  cost  of  producing 
heat. 

Relative  Cost  of  Heat   for  Incubatlnsr. 

Approximate  Cost. 
Method   of  Heatine-.  Per   100  Eggs. 

600   B.t.u.    gas    at    $1.50    per    1000    cu.    ft 37c 

600  B.t.u.    gas    at    $1.00    per    1000    cu.    ft 25c 

Coal  oil  at  20c  per  gallon 20c 

Electricity   at    5c    per    kw.-hr 50c 

Electricity    at    3c    per    kw.-hr 30c 

Electricity    at    2c    per    kw.-hr 20c 

Brooding  of  Chickens. — The  chick  which  is  taken 
from  the  incubator  to  the  brooder  at  the  age  of  twenty- 


192  ELECTRIC     HEATING 

four  hours  (and  known  as  a  "day  old  chick")  is  not 
fed  for  another  similar  period  or  until  the  'chick  is 
about  forty-eight  hours  old.  The  reason  for  this,  is 
that  the  chick  has  absorbed  the  yolk  of  the  egg  into 
its  digestive  organs  just  prior  to  pipping,  and  contin- 
ues to  live  on  this  food  for  the  entire  forty-eight  hours. 
The  chick's  first  meal  should  consist  of  grit,  such  as 
coarse  sand,  after  which  it  may  be  fed  some  good  chick 
food. 

The  temperature  of  the  brooder  should  be  kept  at 
^l^out  95°  F.  for  the  first  week  and  gradually  dropped 
for  the  next  five  weeks  or  until  the  chick  is  sufficiently 
matured  to  roost.  It  is  important  to  watch  the  tem- 
perature carefully  with  very  young  chicks,  because 
otherwise  they  will  become  restless  and  crowd  to- 
gether as  soon  as  their  backs  get  cold.  If  the  crowd- 
ing becomes  too  severe,  the  chicks  will  sweat  and 
become  weak  and  the  less  rugged  ones  may  be  smoth- 
ered. 

A  chick  demands  plenty  of  oxygen,  (about  10 
times  as  much  as  a  person  in  proportion  to  its  weight), 
and  if  it  is  to  mature  rapidly  and  develop  good  lungs, 
the  brooding  must  be  done  in  a  well  ventilated  room. 
The  chick  should  not  be  subjected  to  drafts  of  air, 
however,  and  best  results  are  secured  in  a  room  hav- 
ing a  tight  floor  and  provided  with  high  ventilation. 
The  temperature  of  the  room  is  immaterial  as  long 
as  the  proper  degree  of  heat  is  maintained  inside  the 
brooder.  Coarse  straw  or  sand  is  usually  spread  out 
beneath  the  brooders. 

Electric  Brooders. — These  devices  are  l)uilt  in 
round,  square,  or  oblong  shapes,  and  in  capacities  of 
from  50  to  1200  chicks.  The  tops  of  the  hovers  are 
usually  made  of  wood  insulated  beneath  with  asbestos, 
and  supported  on  short  wood  or  metal  legs.  Strips 
of  canvas  or  oilcloth,  wide  enough  to  reach  the  floor 
and  retain  the  heat,  are  fastened  around  the  outer 
edges,  and  slitted  perpendicularly  every  few  inches  to 
allow  the  chicks  to  pass  in  and  out  readily. 

In  the  circular  type  hover,  the  heating  element  is 
placed   in   the   center  of  the   top,   and   in   other   types 


INCUBATING     AND     BROODING 


193 


coiled  wire  heating  elements  are  arranged  around  the 
top,  in  order  to  secure  a  wider  distribution  of  heat. 
The  air,  when  heated,  banks  against  the  insulated  top 
and  settles  down  upon  the  backs  of  the  chickens.  One 
or  more  holes  are  generally  drilled  in  the  floor  be- 
neath the  machines  to  introduce  a  proper  amount  of 
fresh  air  inside. 


RfCtunKular    Type   Cliick    Kroo  1( 


in    Operation. 


The  thermostat  for  regulating  the  temperature 
inside  the  hover  is  mounted  a  few  inches  below  the 
top  and  adjusted  by  a  screw  on  the  outside. 

A  well  constructed  brooder  is  usually  provided 
with  about  100  watts  capacity  per  hundred  chicks. 
The  current  consumption  has  been  found  to  average 
about  20  kw  -hr.  per  hundred  chicks. 


Esco    100   Chick  Hover. 


Advantages  of  Electric  Brooders. — Almost  all  the 
advantages  that  apply  to  electric  incubators,  apply  as 


194 


ELECTRIC     HEATING 


well  to  electric  brooders.     They  save  time,  labor,  and 
anxiety.     They   insure   even   heat   distribution,   easily 


Round  Type  Electro-Hatch  Hover  in  Operation. 


Electio-Hatch  Rectangular  Type  Brooders  in  Operation. 

controlled  temperatures,  and  elimination  of  fire  hazard. 
The  electric  heat  neither  burdens  the  atmosphere  with 


INCUBATING     AND     BROODING 


195 


poisonous  fumes,  nor  destroys  its  oxygen.  It  has  fur- 
thermore been  demonstrated  in  actual  practice,  that 
an  electrically  brooded  chicken  is  usually  ready  for 
the  roost  about  two  weeks  sooner  than  one  brooded 
by  fuel  heat,  and  is  universally  stronger  and  more 
vigorous. 

Statistics  show  that  an  average  of  less  than  50  per 
cent  of  the  baby  chicks  placed  under  the  many  types 


'•** 


r 


Interior  of  Brooding  House,  Baywood  Poultry  Farm, 
San    Mateo,    Cal. 

of  brooders  now  in  use  are  raised  to  the  roosts,  whereas 
actual  tests  made  during  the  past  eighteen  months 
with  a  large  number  of  electric  brooders  show  that 
the  proportion  has  been  raised  by  their  use  to  better 
than  85  per  cent. 

Relative  Costs  of  Operation. — The  following  will 
give  an  idea  of  the  relative  costs  of  fuel  and  electric 


196  ELECTRIC     HEATING 

Operation  of  brooders.  The  data  are  'averaged  from 
many  figures  secured  in  actual  practice,  and  are  based 
on  an  assumed  outside  temperature  of  50°  F. 

Relative  Co8«m  of  Heat  for  Brooding. 

Approximate   Cost 
Method    of    Heating.  per   100  Chicks. 

Artificial  600  B.t.u.   gas  at   $1.50   per   1000  cu.   ft..    $1.50 
Artificial  600  B.t.u.   gas  at   $1.00  per   1000   cu.   ft..      1.00 

Coal   oil   at   20c  per   gallon 1.40 

Distillate    at    8c   per    gallon 4  5 

Distillate  at  8c  per  gallon   (blue  flame  burner) 15 

Electricity  at  5c  per  kw.-hr 1.00 

Electricity  at  3c  per  kw.-hr 60 

.  .Electricity  at  2c  per  kw.-hr 40 

It  is  apparent  that,  although  electric  energy  may 
have  to  be  purchased  at  a  low  rate  to  compete  with 
fuel  on  the  basis  of  actual  cost  of  heat  energy,  the 
advantages  accruing  to  the  user  of  electrically  heated 
apparatus  will  more  than  oflfset  this  added  expense. 


I 


CHAPTER  XIV 

ELECTRIC  WELDING. 

Nature  of  Welding. — When  two  pieces  of  metal 
are  heated  to  the  proper  temperature,  brought  into 
contact,  and  united  into  one  solid  piece,  the  process 
is  called  welding.  The  essential  feature  is  that  of 
bringing  the  pieces  of  metal  to  the  proper  temperature 
so  that  they  will  tend  to  flow  together  and  cohere.  All 
the  processes  that  have  been  devised  are  simply  re- 
quired for  producing  heat. 

Metals  may  usually  be  most  easily  welded  when 
in  a  plastic  condition.  Whereas  welding  processes 
were  formerly  limited  to  such  metals  as  iron,  nickel, 
platinum,  and  gold,  the  high  temperatures  now  avail- 
able have  made  it  possible  to  weld  almost  all  the  metals 
and  a  large  percentage  of  the  metallic  alloys. 

Welding  Processes. — A  general  classification  of 
commercial  methods  of  welding  may  include  smith 
welding,  hot  flame  welding,  chemical  welding,  and 
electric  welding. 

Smith  welding  or  forging  is  the  process  of  joining 
pieces  of  metal  by  hammering  them  into  shape.  It  is 
one  of  the  oldest  arts,  depends  for  its  success  on  the 
operator's  skill,  is  usually  expensive,  and  is  more 
adaptable  to  small  than  to  heavy  work. 

Hot  flame  or  gas  welding  has  numerous  commer- 
cial applications  and  may  be  used  for  many  kinds  of 
work  that  cannot  be  done  by  forging.  The  most  impor- 
tant methods  are  the  oxy-acetylene,  oxy-hydrogen,  oxy- 
pintsch  gas,  and  oxy-blau-gas.  As  the  names  indicate, 
welding  heat  is  produced  in  each  process  by  mixing 
oxygen  and  another  gas  in  suitable  burners.  The  gases 
are  usually  compressed  and  stored  in  strong  cylinders. 
The  various  processes  may  be  used  for  cutting  as  well 
as  for  welding.    The  principal  advantages  are  less  first- 


198  ELECTRIC     HEATING 

cost,  simplicity,  light  weight,  high  flame  temperature, 
flexibility,  and  portability  of  apparatus.  The  disad- 
vantages are  high  operating  cost,  carbonization,  oxi- 
dation, cracking  of  the  welds,  and  danger  of  fire  and 
explosions  from  the  flames  and  gases. 

Chemical  welding  is  limited  in  its  commercial  ap- 
plication to  the  process  known  as  thermit  welding, 
or  "cast  welding,"  which  consists  in  igniting  a  mix- 
ture of  aluminum  and  iron  oxide  in  a  suitable  mold. 
The  intense  heat  produced,  causes  the  aluminum  to 
reduce  the  iron  from  the  oxide,  and  forms  a  molten 
mass  of  thermit  steel  which  is  run  into  and  around 
the  parts  to  be  welded.  The  process  lends  itself  bet- 
ter to  the  welding  of  larger  articles  than  smaller  ones, 
but  in  any  case  it  is  both  slow  and  expensive. 

Electric  welding,  with  which  this  chapter  deals, 
although  a  relatively  new  commercial  application,  is 
rapidly  becoming  one  of  the  most  important  of  all  the 
welding  processes.  The  chief  advantages  are  low  oper- 
ating cost,  wide  range  of  application,  flexibility  and 
ease  of  temperature  control,  less  harmful  oxidation 
and  carbonization,  and  less  expansion  and  contraction 
of  the  parts  welded.  The  disadvantages  are  higher 
first  cost,  and  greater  weight  and  lack  of  portability 
of  apparatus.  Electric  welding  machines  may  ordi- 
narily be  classified,  either  as  arc  welding,  or  as  resist- 
ance welding  apparatus.  In  the  former  heat  is  pro- 
duced by  means  of  an  electric  arc,  whereas  in  the  latter, 
heat  is  produced  by  the  resistance  to  the  flow  of  cur- 
rent at  the  contact  between  the  parts  to  be  welded. 

Arc  Welding. — The  electric  arc  may  be  used  for 
welding  practically  all  the  metals.  The  commercial 
processes  are  usually  performed  by  melting  material 
into  openings  or  crevices,  or  of  fusing  down  the  body 
of  an  article  to  fill  such  openings.  There  are  a  great 
many  practical  applications  of  arc  welding  apparatus, 
both  in  manufacturing  and  repairing. 

Direct  current  of  high  amperage  and  low  voltage 
(usualy  30  to  75  volts)  is  employed.  The  amount 
of  current  required  depends  upon  the  kind  of  material, 
size  of  the  weld,  and  speed  of  operation  desired. 


ELECTRIC     WELDING 


199 


Lincoln    Arc   Welder    (complete    with    panel   board). 


Systems  of  Arc  Welding. — There  are  two  impor- 
tant welding  processes,  known  as  the  Benardos  or 
graphite  process,  and  the  Slavianoff  or  metallic  pro- 
cess. In  both  systems  the  article  to  be  welded  is  con- 
nected to  the  positive  side  of  the  circuit,  and  the  elec- 
trode to  the  negative  side.     The  arc  is  produced  by 


200 


ELECTRIC     HEATING 


bringing  the  negative  electrode  in  contact  with  the 
work  and  quickly  withdrawing  it  a  short  distance. 
Since  the  positive  terminal  of  an  arc  is  the  hotter,  the 
heat  is  produced  where  it  can  be  most  effectively  util- 
ized. 

The  graphite  process  makes  use  of  a  carbon  elec- 
trode. After  the  arc  is  drawn,  filling  material  in  the 
form  of  a  ''melt  bar''  is  fused  into  place  by  the  heat 
produced.  This  process  may  be  used  for  welding 
aluminum,  copper  alloys,  cast  iron,  and  other  metals 
which  do  not  volatilize  very  readily.  The  arc  should 
be  moved  about  over  the  surface  to  prevent  burning, 
and  to  cause  the  slag  or  other  impurities  to  flow  to 
one  side. 


Operator  at  W^ork  WMth  General   Electric  Arc  Welder. 


ELECTRIC     WELDING 


201 


The  metallic  process  makes  use  of  a  metallic  pen- 
cil electrode,  (usually  iron  or  steel),  which  gradually 
melts  from  the  heat  of  the  arc,  and  forms  the  filling 
material.  The  current  required  is  much  less  than  for 
the  graphite  process  but  the  speed  is  also  less  for  heavy 
work.  The  principal  application  of  this  process  has 
been  in  sheet  metal  work,  where  the  electrode  is  de- 
posited along  the  joints  or  seams.  It  is  also  used  for 
building  up  worn  pieces,  and  filling-  holes  in  castings. 

Another  system  of  welding  which  has  not  been  ap- 
plied very  extensively  in  this  country  is  the  Zerener 
process,  wherein  an  arc  is  drawn  between  two  car- 
bon electrodes  and  deflected  downward  against  the 
work  by  a  magnet.  Its  use  is  limited  to  light  work, 
but  it  is  claimed  that  somewhat  finer  work  can  be 
done  by  adjustment  of  the  magnet. 

Arc  Welding  Apparatus. — In  making  a  choice  of 
equipment,  careful  consideration  must  be  given  to  the 
character  of  work  to  be  done.  All  arc  welding  ma- 
chinery is  designed  to  take  the  available  energy  supply 


Repairing-  Steel  Casting-  with  the  Lincoln  Arc  Welder. 


202  ELECTRIC     HEATING 

and  deliver  it  in  proper  form  for  welding-  work.  In 
the  simplest  forms  of  apparatus,  the  current  may  be 
cut  down  to  the  proper  voltage  by  the  use  of  either 
a  water  rheostat  or  a  heavy  resistance  connected  in 
series  with  the  arc.  When  this  is  done  considerable 
energy  is  wasted  in  heating  the  water  or  other  resist- 
ance materia! 

Low  voltage  motor-generator  sets  are  often  used 
on  account  of  their  higher  efficiency  and  greater  ease 
of  control.  The  generators  are  usually  compound 
wound,  although  when  used  on  an  individual  welding 
circuit,  they  may  be  shunt  wound.  The  compound 
wound  generator  gives  more  accurate  voltage  regula- 
tion and  is  usually  employed  where  more  than  one 
welding  circuit  is  provided  with  energy  from  the  same 
machine.  Where  several  circuits  are  supplied  from  a 
single  motor-generator  set,  the  current  on  each  cir- 
cuit must  be  regulated  by  the  use  of  special  resistances, 
which  naturally  causes  a  waste  of  energy. 

Some  welding  machines  are  provided  with  current 
through  s3mchronous  converters,  but  the  regulation 
is  less  satisfactory  and  they  cannot  be  used  as  well 
for  finer  classes  of  work. 

Generators  used  for  welding  are  sometimes  spe- 
cially wound  for  variable  voltage  operation  so  that  no 
resistance  is  required.  It  is,  however,  necessary  to 
provide  separate  machines  for  each  individual  oper- 
ator. 

Either  graphite  or  metallic  electrodes  may  be  used 
with  practically  all  arc  welding  equipments. 

Each  manufacturer  of  welding  machinery  offers  its 
apparatus  on  the  strength  of  some  peculiarity  of  the 
controlling  apparatus  or  design  of  the  machines,  and 
the  user  should  consider  the  class  of  work  to  be  per- 
formed before  deciding  upon  the  type  of  machinery 
to  install. 

The  current  consumption  varies  with  the  nature 
of  the  material  welded,  the  shape  and  size  of  the  piece, 
and  the  nature  of  the  operation.  Metallic  welding  pro- 
cesses may  require  from  15  to  150  amperes,  and  graph- 
ite welding  from  100  to  700  amperes. 


ELECTRIC     WELDING  203 

Costs  of  Arc  Welding. — The  nature  of  the  work, 
the  cost  of  energy,  and  the  operator's  skill,  each  have 
much  to  do  with  the  cost  of  welding.  It  may  ordi- 
narily be  done  in  less  time  and  at  from  10  per  cent 
to  75  per  cent  of  the  average  cost  of  acetylene  welding. 
The  following  tables  show  the  cost  of  several  arc 
welding  jobs  where  labor  was  figured  at  thirty  cents 
per  hour,  energy  at  two  cents  per  kw  -hr.,  and  filling 
material  at  eight  cents  per  pound.  The  first  table 
shows  the  time  and  cost  of  welding;  the  second  table, 
the  savings  efifected  over  methods  previously  employed, 
and  the  third  table  the  savings  efifected  by  repairing 
electric  railway  apparatus  as  against  purchase  of  new 
])arts. 

TABLE    I.* 

Time  and   Cost  of  Welding. 

Article   Welded.  Time.  Cost. 

Steel  casting,  shrinkage  crack  6  in.  long  by  1  in.  deep....  8  min.  $00.04 

Steel  casting,   riser,   4   in.   by   4   in.   cut   off 4  min.  .05 

Forged  steel  locomotive  frame,  broken  in  two  places 20   hrs.  18.28 

12  in.  crack  in  back  sheet  of  locomotive  boiler 9  hrs.  5.47 

Building  up  worn  driving  wheel  instead  of  turning  down.  ...  2  hrs.  .72 

Welding  67  cracks  in  old  fire  box   (saving  over  $1000)  ....  2  wks.  52.60 

Cast-steel  tender  frame,   broken  in  three  places 27  hrs.  19.00 

Steel  shaft,  2  in.  diameter,  broken,  welded  ready  to  finish .  .  1  hr.  .60 

Broken  railway  type  motor  case,  cast  steel, welded 3  hrs.  1.95 

Enlarged  holes  in  brake  levers,  steel  bars 4  min.  .05 

Building  up  2  in.  armature  shafts,  worn  in  journals 3  hrs.  1.80 

Air  brake  piston  rods,  broken,  welded  ready  to  finish 30  min.  .35 

Leaking  axle  boxes,  welded  in  position 15  min.  .15 

TABLE  II.* 

Relative  Costs  of  Repairs. 

Article    Welded.  Welding.  Old  Cost.  Saving. 

Engine  main  frames,  both  broken $11.80  $56.20  $44.40 

Driving  wheels,  built  up  3/16  in.  on  tread.  .           .72  8.00  7.28 

General  repairs   on  fire  box  side   sheets....      66.51  342.62  276.11 

Filling  worn  knuckle  joint  bushing  hole.  .  .  .           .75  7.50  6.75 

Welding  7  cracks  in  locomotive  cylinder 22.35  367.15  344.50 

Broken    mud   ring   en    locomotive    boiler....       32.07  118.06  85.99 

TABLE    III.* 

Street  Railway  Repairs. 

Article    Welded.                                                Welding.  New  Part.  Saving. 

Armature    shaft,    repaired    in   place $1.70  $    4.72  $   3.02 

Armature   shaft,   large,   repaired   in  place....      1.97  15.13  13.16 

Kailway   motor   axle   cap,    large 22  3.51  3.29 

Railway    motor    armature    bearing    cap .27  6.07  5.80 

Railway  motor  gear  case,  top  half .48  7.30  6.82 

Truck  side  frame.  Brill   27-G 72  44.40  43.68 

Truck  side  frame,  Peckham  14-B 90  46.98  46.08 

Brake  head,  building  up  worn  socket 06  1.15  1.09 

Motor  frame,   G.   E.   90,  railway  type  motor.  .       2.88  16.80  13.92 

*From   "Applied  Electrochemistry  and   Welding." 

Arc  Welding  Operations. — Metallic  electrodes  are 
used  almost  exclusively  for  thin  plate  and  sheet  weld- 


204  ELECTRIC     HEATING 

ing.  The  speed  at  which  the  work  can  be  done,  depends 
upon  the  kind  and  thickness  of  the  material,  the  kind 
of  weld,  etc. 

Metallic  electrodes  are  usually  employed  in  weld- 
ing the  seams  in  tanks,  boiler  flues,  etc.     The  joints 


^l^^^^^^^^l 


Seam   Welding   With   Lincoln   Arc   Welder. 

have  been  found  to  be  much  stronger  than  riveted 
seams,  and  the  use  of  electric  welding  machinery  for 
this  class  of  work  is  finding  a  very  wide  applica- 
tion. 

(1)   COMPARATIVE  COST — ACETYLENE  AND  ARC  WELDING. 

Acetylene Arc 

Thickness     Ft.  Welded      Cost  per        Amps.     Kw.  Input    Ft.  Welded.      Cost  per 
of  Metal.      per  Hour.     Ft.  Welded,      in  Arc.     M.  G.  Set.     Per.  Hour,  Ft,  Welded, 

1/16  in.  25  $0,018  70  3.0  25  $0,014 

1/8  in.  15  .047  80  3.2  15  .024 

1/4  in.  6  .187  110  4.15  8  .048 

3/8  in.  4  .420  120  4.64  7  .056 

5/8  in.  2  1.510  150  5.75  6  .070 

These  data  were  obtained  with  a  Lincoln  welding" 
machine  and  were  based  on  the  following  costs : 

Acetylene,    1.555   B.t.u Ic  per  cu.   ft. 

Oxygen    2c   per  cu.   ft. 

Electricity    2c  per  kw  -hr. 

Labor    30c  per  hour. 

In  welding  most  large  iron  and  steel  castings,  the 
carbon  electrode  and  melt  bar  are  employed,  although 


ELECTRIC     WELDING 


20: 


the  metallic  electrode  may  be  used  for  light  work.  A 
space  sufficiently  large  to  work  in  should  be  prepared, 
because  the  filling  material  will  not  flow  in  small 
crevices.  Cast  iron  should  usually  be  heated  before 
and  annealed  after  welding  in  order  to  prevent  cracks, 
and  to  soften  the  v;eld  for  machining.  The  use  of  a 
welding  flux  will  ordinarily  improve  the  quality  of  a 
cast  iron  weld  by  raising  the  slag. 


Welding  With  the  Electric  Arc. 


The  operation  of  welding  aluminum,  copper,  and 
various  alloys,  is  somewhat  similar  to  that  employed 
for  iron  and  steel  castings.  The  work  is  usually  placed 
in  a  horizontal  position  and  the  filling  puddled  in  by 
the  graphite  electrode  method.  Very  thin  sheets,  less 
than  one-eighth  inch  in  thickness,  cannot  be  welded  by 
this  means.  Larger  amounts  of  current  should  not 
be  used  than  are  required  to  melt  the  metal,  and  in 
welding  alloys  care  should  be  exercised  to  prevent 
volatilization  of  any  of  the  metallic  constituents. 


206 


ELECTRIC     HEATING 


Arc  Cutting. — The  electric  arc  may  be  utilized  to 
great  advantage  for  cutting  metals  in  foundries,  scrap 
yards,  and  similar  places.  The  rate  -of  cutting  iron 
and  steel  is  ordinarily  about  one  square  inch  of  cross 
section  per  minute  per  hundred  amperes.  The  graph- 
ite electrode  is  employed  for  this  work  and  current 
varying  in  quantity  from  100  amperes  to  1000  amperes 
may  be  employed.  The  electric  arc  cuts  a  wider 
groove  than  the  gas  flame,  but  has  an  advantage  in 
that  it  does  not  destroy  the  metal  that  is  melted. 

Resistance  Welding. — This  process  is  quite  unlike 
arc  welding.  It  consists  in  passing  a  current  through 
a  contact  between  the  metals  to  be  welded.  The  re- 
sistance to  the  flow  of  energy  being  greater  at  the 
point  of  contact,  the  metals  heat  up  until  a  welding 
temperature  is  attained  when  they  are  forced  together 


Wi 


■;;)!;>!;;m})!idm^!<^;;fmM 


Principle    of   Spot   Welding.      (Heavy   current   and 

sure  applied  between  A  and  B  cause  the  metallic 
plates  to  heat  up  and  weld  at  the  point  of  applica- 
tion as  shown.) 

with  sufficient  pressure  to  cause  them  to  adhere.    This 
is  usually  known  as  the  Thomson  system. 

Alternating  current  of  low  voltage,  (usually  from 
3  to  5  volts),  is  employed  in  resistance  welding.  The 
work  is  ordinarily  done  rapidly,  because  heavy  cur- 
rents and  high  pressures  may  be  applied. 


ELECTRIC     WELDING 


207 


Resistance  Welding  Apparatus. — The  equipment 
for  electric  resistance  welding  requires  machines  espe- 
cially adapted  to  the  work  in  hand.  The  frame  is 
usually  provided  with  a  clamping  device  for  holding 
the  parts,  and  a  means  for  applying  pressure  after 
they  have  been  heated.  A  transformer  for  reducing 
the  voltage  on  the  circuit,  together  with  a  main  con- 
trol switch,  and  some  means  of  regulating  the  flow 
of  current,  are  ordinarily  supplied  with  the  machine. 

Manufacturing  Applications. — Resistance  welding 
is  limited  almost  exclusively  to  new  work  of  moderate 


Winfield   S-12   Spot  Welder. 


208 


ELECTRIC     HEATING 


size.  Practically  every  kind  of  metal,  and  many  alloys 
and  combinations  of  metals  may  be  welded,  if  the  sur- 
faces can  be  joined  and  the  parts  manipulated  in  the 
machines. 

A  few  of  the  many  applications  of  resistance  weld- 
ing apparatus  are  as  follows : 


Wire   Rings,   Flat   Hoop,    Small   Carriage   Tire   and   Steel 
Cylinder  Welded   With   a   Thomson   Welder. 


I 


ELECTRIC     WELDING  209 

Rail  bonds.  Wagon  tires.  Iron  beds. 

Automobile  parts.  Shovels.  Wheelbarrow  bodies. 

Structural  iron  work.Iron  wheels.  Cooking  utensils. 

Pipes.  Typewriter  parts.       Chains. 

Screens.  Stove  pipe  Valve  heads. 

Axles.  Steel  shelves.  Knives. 

Umbrella  rods.  Steel  lockers.  Boilers. 
Sheaves. 

Classification  of  Resistamce  Welds. — The  original 
method  was  known  as  butt  welding,  and  consisted  in 
bringing  the  pieces  together  either  end  wise  or  edge 
wise.  After  they  became  heated  they  were  forced  to- 
gether. A  process  known  as  spot  welding  was  after- 
wards developed  for  welding  lapped  joints.  It  was 
accomplished  by  making  contact,  about  rivet  size,  be- 
tween the  sheets  of  metal,  passing  a  current  through 
the  contact,  and  applying  pressure  when  the  metal  be- 
came plastic. 

A  number  of  other  kinds  of  welds,  which,  in  a 
more  or  less  degree,  are  modifications  of  the  butt  and 
spot  welds,  have  found  a  very  wide  application.  Lap 
or  seam  welding  consists  in  passing  a  current  through 
a  lapped  seam  and  applying  pressure  by  means  of  rolls. 
Butt  seam  welding,  as  the  name  signifies,  is  a  some- 
what similar  process.  Cross  welding  for  making 
screens,  etc.,  and  tee  and  jump  welding  for  fastening 
bars  or  pipes  together,  are  other  common  welding  pro- 
cesses. 

Welding  Various  Metals. — Although  most  of  the 
metals  may  be  welded  successfully,  the  commercial  ap- 
plication of  resistance  welding  apparatus  is  usually 
limited  to  only  a  few  of  them.  Iron  and  steel  are  most 
frequently  subjected  to  welding  operations,  and  are 
about  the  easiest  to  handle.  The  pressure  imposed 
should  be  high  and  the  metal  should  be  kept  below 
the  melting  point.  Cast  iron  is  very  difficult  to  weld 
by  the  resistance  process  on  account  of  its  structure 
and  composition.  High  carbon  steel  may  be  welded, 
provided  it  is  afterwards  annealed  to  remove  the 
strains.  Nickel  steel  makes  a  very  strong  weld.  Gal- 
vanized iron  of  moderately  thin  gauge,  may  be  welded. 


210  ELECTRIC     HEATING 

provided  the  joints  are  regalvanized  when  the  opera- 
tion is  completed.  Sheet  aluminum,  brass,  copper, 
iron  and  copper,  and  brass  and  copper,  may  also  be  suc- 
cessfully welded  by  skilled  operators. 


Clamp   for  Thomson    4'0-A  Butt   Welder. 

Spot  and  butt  welding  operations  are  limited  in  the 
extent  to  which  they  can  be  applied  commercially.  If 
the  metals  are  very  thick,  the  amount  of  energy  re- 
quired will  be  very  large,  and  the  radiation  losses  from 
the  metals  and  the  cooling  water  will  become  ex- 
cessive. 


ELECTRIC     WELDING 


211 


Character  of  Resistance  Welds. — If  the  weld  is 
upset  so  that  its  cross  sectional  area  is  slightly  greater 
than  that  of  other  portions  of  the  piece,  the  joint  should 

When  finished 


have  as  much  strength  as  the  stock 


Winfield   BB-255    Butt   Welder. 


to  the  same  diameter  as  the  stock,  it  should  have  a 
strength  efficiency  of  from  7^  per  cent  to  90  per  cent. 
Ordinarily  the  strength  of  a  weld  may  be  improved  by 
working.  Care  should  be  exercised  to  prevent  heating 
the  material  too  hot,  or  the  weld  may  be  burnt  and 
thereby  w^eakened. 


212 


ELECTRIC     HEATING 


Butt  and  Spot  Welding  Costs. — The  average  costs 
of  resistance  welding  are  shown  in  the  two  following 
tables,  which  are  figured  on  the  basis  of  an  energy 
rate  of  two  cents  per  kilowatt-hour. 


Butt  Welder   Data. 


Rd.  Iron 

Cost 

Diamter 

Kilowatts 

Time  in  Seconds 

per  1000  Welds 

in  Inches. 

Required. 

to  Make  Weld. 

2'.  Cents  per  kw. 

% 

2 

3 

0.04 

Vz 

5 

5 

0.14 

% 

12 

15 

1.00 

1 

18 

20 

2.00 

IV2 

50 

40 

11.10 

2 

75 

50 

20.84 

Spot 

Welder  Data, 

Cost  per 

Gauges 

Thickness  in 

Approximate 

Time  in 

1000  Welds 

of  Sheet 

Fractions 

Kilowatts 

Seconds  to 

at  2  Cents 

Steel. 

of  an  linch. 

Capacity. 

Make  a  Weld. 

per  kw. 

28 

1-64 

5 

.3 

0.009 

24 

1-40 

7 

.5 

0.02 

20 

3-80 

9 

.7 

0.035 

16 

1-16 

12 

.9 

0.06 

10 

9-64 

18 

1.5 

0.15 

6 

13-64 

28 

4.0 

0.62 

Energy  Requirements  and  Character  of  Load. — 

Electric  current  is  usually  supplied  to  the  machines 
at  a  pressure  of  220  volts,  which  for  ordinary  welding 
operations,  is  reduced  to  from  3  to  5  volts. 

The  power  required  for  resistance  welding  opera- 
tions depends  upon  the  kind  of  material,  the  area  of 
cross  section  of  the  pieces,  and  the  time  taken  for  mak- 
ing the  weld.  The  following  table  shows  the  average 
power  and  time  required  for  butt  welding: 

Power  and  Time  for  Butt  Welding  Iron  and  Steel. 

Area.  Sq.  In  Power,  kw.  Seconds.  Horsepower. 

0.5  10.0  28  13.5 

1.0  18.75  40  25  0 

2.0  33.00  57  44.0 

4.0  56.3  80  76.0 

6.0  69.0  98  92.5 

Power   and   Time   for   Butt   Welding    Brass. 


oa.  Sq.  In 

Power,  kw. 

Seconds. 

Horsepower. 

0.25 

12 

14 

15.7 

0.50 

15 

20 

20.0 

1.00 

29.5 

28 

39.5 

2.00 

53 

40 

71,0 

3.00 

66 

49 

88.5 

Power  and   Time  for   Butt  Welding   Copper. 

Area.  Sq.  In  Power,  kw.  Seconds.  Horsepower. 

0.125  8.5  7  11.5 

0.250  18  10  24.0 

0.500  82  14  43.0 

1.00  55.5  20  75.0 

1.50  68  25  91.0 


ELECTRIC     WELDING 


213 


The  character  of  resistance  welding  power  loads 
depends  largely  upon  the  work  that  is  being  done.  It 
is  naturally  very  unsteady,  and  somewhat  inductive. 


Unfinished    Forgings    of   Meat    Saw    Back,    S^/^-in.    Ring 

and    Two    Single    Throw    Cranks    Welded    With 

Thomson   Welder. 


CHAPTER  XV 

ELECTRIC  STEAM  BOILERS. 

Application. — Where  conditions  are  sucli  that  elec- 
tric energ-y  may.  be  obtained  at  low  cost  during  off 
peak  periods  or  otherwise,  or  where  only  a  small  quan- 
tity of  steam  is  required  for  certain  operations,  electric 
steam  boilers  may  often  'be  used  advantageously. 

Industrial  plants  require  steam  for  numerous 
purposes  other  than  that  of  simply  driving  engines. 
Many  machines,  such  as  laundry  apparatus  and  simi- 
lar devices,  may  use  steam  heat  to  better  advantage 
than  the  usual  form  of  electric  heat.  Where  this  con- 
dition obtains,  steam  boilers  may  be  heated  electrically 
to  effect  the  desired  results. 

Although  electric  steam  boilers  have  not  yet  been 
applied  very  generally  in  the  industrial  field  it  is  prob- 
able that  the  superior  advantages  which  they  afford 
will  tend  to  bring  them  into  wider  use. 

Advantages. — The  inherent  features  of  electric 
steam  boilers  which  commend  them  for  industrial  pur- 
poses are  their  efficiency  of  operation  (often  as  high  as 
95  per  cent),  the  reduction  of  labor  cost,  (no  firemen 
needed),  the  safety  of  operation,  (no  danger  of  fire) 
and  the  convenience  of  location.  As  usual  where  elec- 
tric heat  supplants  fuel  heat  the  annoyance  di  fuel 
burners,  the  heated  atmosphere  and  the  dirt  are  done 
away  with.  The  boilers  may  be  installed  in  any  con- 
venient location  and  in  places  where  other  generators 
would  be  entirely  impractical. 

Steam  Boiler  Calculations. — In  order  to  make  in- 
telligent recommendations  for  steam  boiler  installa- 
tions it  is  necessary  to  know  something  of  the  funda- 
mental principles  of  steam  generation,  the  customary 
methods  of  rating  the  apparatus,  and  how  to  calculate 
the  capacities  required.  The  most  important  features 
to  be  considered  together  with  some  elementary  defi- 


ELECTRIC     STEAM     BOILERS 


215 


nitions,  tables,  and  practical  examples  are  therefore 
set  forth  for  the  convenient  reference  of  those  less 
conversant  with  the  subject. 

Boiler  Efficiencies. — The  definition  of  steam  boiler 
efficiency  is  the  ratio  of  the  heat  absorbed  by  the  boiler 
in  producing  steam  to  the  total  amount  of  heat  avail- 
able. As  electric  steam  boilers  are  usually  well  lagged 
and  equipped  with  immersion  heaters  it  is  apparent 
that  practically  all  the  energy  applied  is  absorbed  by 


G.  E.  S'team  Boiler  in  Laundry  of  Estes  Park   (Colo.)   Hotel. 


the  boiler  in  producing  steam.  The  efficiency  of  elec- 
tric boilers,  therefore,  may  be  as  high  as  95  per  cent. 
The  efficiency  of  a  fuel-fired  boiler,  on  the  other  hand, 
may  vary  anywhere  from  50  per  cent,  or  even  less, 
to  80  per  cent,  depending  upon  the  method  of  firing, 
the  kind  of  combustible  consumed,  and  the  numerous 
losses  of  heat,  the  chief  of  which  is  that  due  to  the 
temperature  of  the  chimney  gases. 

Boiler  Horsepower. — The  function  of  a  boiler  is 
that  of  producing  steam  by  the  evaporation  of  water 
and  the  term  horsepower,  having  to  do  with  the  rating 
of  boilers,  should  not  be  confused  with  the  term  horse- 
power relating  to  prime  movers.  Boiler  horsepower  is 
a  measure  of  evaporation  arid  not  of  power.   It  is  equal 


216  ELECTRIC     HEATING 

to  an  evaporation  of  34.482  pounds  of  water  per  hour 
from  and  at  212°  F.  Since  970.4  B.t.u.  (latent  heat  of 
evaporation)  are  required  to  evaporate  a  pound  of 
water  at  atmospheric  pressure  after  it  has  attained  a 
temperature  of  212°  F.,  it  is  apparent  that  a  boiler 
horsepower  is  equivalent  to  34.482  X  970.4  or  33,461 
B.t.u. 

Factors  of  Evaporation. — In  order  to  calculate  the 
amount  of  water  that  a  boiler  of  a  certain  horsepower 
rating  will  evaporate  per  hour  when  supplied  with 
water  at  a  certain  temperature  and  operated  at  a  cer- 
tain pressure,  it  is  necessary  to  divide  by  the  corres- 
ponding factor  of  evaporation  found  in  Table  I. 


TABLE  I. 

Factars 

of  Evaporation. 

(Calculated  from 

Marks  and 

Davis  TabL 

es.) 

Feed 

Temp. 

\awe    Steam 

Prespure  — 

Deg.  F. 

50 

60 

70 

80 

90 

100 

32 

1.2143 

1.2170 

1.2194 

1.2215 

1.2233 

1.2251 

40 

1.2060 

1.2087 

1.2111 

1.2131 

1.2150 

1.2168 

50 

1.1957 

1.1984 

1.2008 

1.2028 

1.2047 

1.2065 

60 

1.1854 

1.1881 

1.1905 

1.1925 

1.1944 

1.1961 

70 

1.1751 

1.1778 

1.1802 

1.1822 

1.1841 

1.1859 

80 

1.1548 

1.1675 

1.1699 

1.1720 

1.1738 

1.1756 

90 

1.1545 

1.1572 

1.1596 

1.1617 

1.1636 

1.1653 

100 

1.1443 

1.1470 

1.1493 

1.1514 

1.1533 

1.1550 

Assume  a  boiler  of  5  h.p.  rating  supplied  with 
feed  water  at  50°  F.  and  operated  at  60  pounds  gauge 
pressure.  The  boiler  will  evaporate  5  X  34.482/1.1984 
=  -  143.9  pounds  of  water  per  hour. 

(The  same  boiler  would,  of  course,  evaporate  5  X 
34.482=172.4  pounds  of  water  per  hour  if  supplied 
with  feed  water  at  212°  F.  and  operated  at  zero 
pounds  pressure). 

Calculating  Boiler  Capacity. — It  is  necessary  to 
kno'w  three  things  in  order  to  calculate  the  boiler 
rapacity  required  for  any  purpose  with  any  degree  of 
accuracy — (1)  the  boiler  feed  water  temperature,  (2) 
the  steam  pressure  desired,  and  (3)  the  number  of 
pounds  of  water  that  is  to  be  evaporated  per  hour. 
The  process  is  as  follows : 

(1)  Find  the  factor  of  evaporation  from  Table  I 
corresponding  to  the  temperature  and  pressure  given. 


ELECTRIC     STEAM     BOILERS  217 

(2)  Multiply  the  pounds  of  water  evaporated  by 
the  factor  of  evaporation  and  divide  by  34.482.  The 
result  will  be  the  required  boiler  capacity  (neglect- 
ing losses  in  steam  distribution). 

In  case  the  number  of  pounds  and  character  of 
fuel  consumed  under  a  boiler  are  known,  the  approx- 
imate boiler  capacity  utilized,  or  the  equiv.alent  ca- 
pacity required,  may  be  determined  as  in  the  follow- 
ing example : 

Assume  boiler  consumes  40  pounds  of  14,000 
B.t.u.  coal  per  hour  with  an  assumed  efficiency  of  60 
per  cent.  Then  40  X  14,000  X  -60  =  336,000  B.t.u.  input. 

Since  one  b.h.p.  =  33,461  B.t.u., 

Then  336,000/33,461  =  10  boiler  horsepower  ca- 
pacity. 

Electrically  Heated  Boilers. — Since  a  boiler  horse- 
power is  equivalent  to  33,461  B.t.u.  per  hour  (the  heat 
required  to  evaporate  34.482  pounds  of  water  from  and 
at  212°  F.),  and  since  one  kilowatt-hour  is  equivalent 


G.   E.   steam  Boiler  Applied   to 
Shoe-Stitching-   Machine. 

to  3412  B.t.u.  per  hour,  it  is  apparent  that  the  capacity 
required  to  operate  a  standard  boiler  at  100  per  cent 
efficiency  is  equal  to  33,461/3,412  =  9.8  kilowatts  per 
boiler  horsepower.  On  the  basis  of  95  per  cent  effi- 
ciency (which  is  a  fair  average  for  electrically  heated 
boilers)  the  capacity  required  would  be  9.8/.95  =  10.3. 


218  ELECTRIC     HEATING 

Comparative  costs  of  operating  fuel  and  electric 
steam  boilers  under  assumed  efficiencies  and  using 
•fuel  and  electricity  at  various  costs  and  rates  are 
shown  in  Table  II. 

TABLE    II. 

Hourly  Operating:  Costs  per  B.H.P.  in  Cents. 

60%  Efficiency — Boiler  Using-  d5%  Efficiency — Boiler  Using 

14,000  B.t.u.  Coal.  3412  B.t.u.  Electricity. 

Cost  of  Fuel  per  Ton.  Cost  of  Current  per  kw-hr. 

$2.50           $5.00          $10.00  Ic                   2c                   3c 

.5c               1.0c             2.0c  10.3c             20.6c             30.9c 

Although  the  cost  of  steam  produced  with  fuel 
is  much  less  than  that  produced  electrically  according 
to  Table  II,  the  labor  cost  and  the  many  disadvantages 
of  fuel  must  also  be  taken  into  accounts  in  making 
intelligent  comparisons. 

Electrical  Energy  Required  to  Evaporate  Water. 
— In  order  to  determine  the  amount  of  energy  required 
to  evaporate  a  certain  weight  of  water  per  hour  sup- 
plied at  certain  temperatures  and  operated  under  cer- 
tain pressures  Table  III  will  be  found  useful. 

TABLE  III. 

Watts    Capacity    Requiretl    to    Evaporate    one    Pound    of    "Water 

per  Hour  Into   Steam  Assuming^  Certain  Initial  Feedwater 

Temperatures   and  Certain   Final   Pressures. 

(Transformation  100%  Efficiency.) 


Lb.  Gauge 

-Initial 

Feed  Water  Temperatures   De^ees  Fahr. 

Pressure. 

40 

50 

60 

70 

80 

90 

100 

110 

0 

334.8 

331.9 

328.9 

326.0 

323.1 

320.2 

317.2 

314.3 

10 

337.7 

334.7 

331.8 

328.9 

326.0 

Si'?3.0 

320.0 

317.2 

20 

339.6 

336.6 

333.7 

330.8 

327.9 

324.9 

322.0 

319.1 

30 

341.0 

338.1 

335.1 

332.2 

329.3 

326.3 

323.4 

320.5 

40 

342.1 

339.2 

336.2 

333.3 

330.4 

327.5 

324.5 

321.6 

50 

343.0 

340.1 

337.2 

334.2 

331.3 

328.4 

325.4 

322.5 

60 

343.8 

340.9 

337.9 

335.0 

332.1 

329.2 

326.2 

323.3 

70 

344.5 

341.5 

338.6 

335.7 

332.7 

329.8 

326.9 

324.0 

80 

345.0 

342.1 

339.2 

336.3 

333.3 

330.4 

327.5 

324.5 

90 

345.6 

342.6 

339.7 

336.8 

333.9 

330.9 

328.0 

325.1 

100 

346.0 

343.1 

340.2 

337.3 

334.3 

331.4 

328.5 

325.5 

Assume  100  pounds  of  water  at  60  degrees  F. 
feedwater  temperature  is  to  be  evaporated  under  70 
pounds  pressure  and  at  an  efficiency  of  95  per  cent. 
The  capacity  required  would  be :  100  (pounds)  X 
338.6  (from  table  III)/.95  (efficiency)  =  35,642  watts 
or  35.642  kw. 

Furthermore,  since  one  boiler  horsepower  is 
equivalent  to   10.3  kw.  at  95  per  cent  efficiency,  the 


ELECTRIC     STEAM     BOILERS 


219 


size  boiler  required  for  the  operation  would  be : 
35.642/10.3  =  3.46  boiler  horsepower. 
These  figures  may  be  checked  by  the  method  sug- 
gested  under   paragraph    headed   "Calculating   Boiler 
Capacities." 

Steam  Boiler  Apparatus. — The  Simplex  and  Gen- 
eral Electric  companies  manufacture  electric  steam 
boilers  in  various  capacities.  They  are  usually 
equipped  with  water  and  steam  gauges,  safety  valves, 
and   other   standard    boiler   fittings.      Simplex   boilers 


G.   E.    Electric   Steam   Boiler. 


are  of  the  horizontal  type  and  are  somewhat  similar 
to  so-called  ''fire  tube  toilers"  in  that  the  heating  ele- 
ments are  inserted  in  longitudinal  tubes  passing 
through  the  shell.  These  tubes  are  welded  in  the 
boilers  and  the  heating  elements  may  be  readily  re- 
moved for  inspection  and  repairs. 

The  General  Electric  boilers  are  of  the  vertical 
type  and  are  usually  heated  by  means  of  direct  immer- 
sion heaters  which  are  inserted  into  the  shell  radially 
and  from  the  outside.  They  are  mounted  in  rows 
around  the  circumference  and  near  the  bottom  of  the 
tank.  The  capacity  of  each  unit  is  one  kilowatt  and 
obviously  a  large  number  are  employed  for  heating 
the  larger  boilers.  The  sizes  and  capacities  of  General 
Electric  steam  boilers  are  set  forth  in  Table  IV. 


220 

ELECTRIC 

HEATING 

TABLE    IV. 

General 

Electric 

Steam  Bollerai. 

Lbs.  Evap. 

Approx. 

per  hr. 

Boiler 

Gallons 

Height 

Floor 

Kw.  Ca- 

From and 

Horse- 

Capacity, 

Over  all 

Space 

No. 

pacity. 

at  212°  F. 

power. 

Full. 

In  Ins. 

In  Feet. 

10 

30 

101 

2.9 

85 

59 

3      x4 

11 

45 

151 

4.4 

110 

66 

3      x4 

12 

60 

201 

5.8 

145 

74 

3^x41/^ 

13 

85 

285 

8.3 

180 

79 

3%x4i^ 

14 

100 

335 

9.7 

250 

85 

4      x5 

15 

150 

503 

14.6 

340 

92 

4^x51/2 

16 

200 

671 

19.5 

480 

104 

5     x6 

To  determine  the  amount  of  water  which  the  different 
sized  boilers  will  evaporate  under  various  pressures  and  with 
various  feedwater  temperatures,  divide  the  figures  in  column  3 
by  the  corresponding  factors  of  evaporation  found  in  Table  I. 

The  boilers  are  all  thoroughly  lagged  with  heat- 
insulating  material.  Although  it  might  be  considered 
unsafe  to  operate  the  present  open  shell  and  fire  tube 
types  of  electric  boilers  at  excessively  high  pressures, 
there  seems  to  be  no  obvious  reason  why  electric 
steam  boilers  might  not  be  designed  on  principles  simi- 
lar to  those  of  water  tube  boilers  and  operated  at  any 
desired  pressures. 


CHAPTER  XVI 

GENERAL  APPLICATIONS  OF  ELECTRIC 
HEAT. 

Diversity  of  Use. — Although  it  is  impossible  to 
enumerate  in  a  single  chapter  the  many  uses  to  which 
electric  heat  has  been  successfully  applied,  a  number 
of  its  possible  applications  in  the  industrial  field  are 
set  forth.  The  descriptions  are  arranged  in  alpha- 
betical order  for  convenient  reference. 

Automobile  Heater. — A  number  of  small  low  watt- 
age heaters  have  been  developed  for  placing  in  auto- 
mobile hoods  to  keep  the  engtines  and  radiators  warm  in 
cold  weather.  These  heaters  keep  the  water  from 
freezing  and  make  the  engines  start  more  easily. 

Bacteriological  Incubators. — Electric  heat  is  par- 
ticularly well  adapted  for  bacteriological  work.     The 


character  of  the  heat  afforded,  the  positive  automatic 
temperature  control  apparatus  available,  and  the  ab- 
sence of  fire  hazard  make  electrically  heated  devices 
of  this  nature  verv  desirable.     A  number  of  bacterio- 


222 


ELECTRIC     HEATING 


logical  ovens  are  in  actual  successful  use  and  the  de- 
sired temperatures  are  maintained  to  within  a  frac- 
tion of  a  degree. 

Bath  Cabinets. — Every  advantage  of  the  Turk- 
ish or  steam  bath  room  is  afforded  by  the  electric  cab- 
inet bath,  and  it  is  being  substituted  for  them  quite 
generally.  The  expense  of  maintaining  hot  air  and 
steam  rooms  and  the  disagreeable  features  attending 
their  use  are  thereby  eliminated  and  the  patients  given 
better  and  more  healthful  treatments. 

The  cabinets  are  usually  constructed  of  wood, 
steel,   or   marble   and    are   designed    for   patient's    use 


Electric    lialh   Cabinet. 


in  either  a  sitting  or  reclining  posture.  The  in- 
teriors are  lined  with  reflecting  surfaces.  Rows  of 
electric  lights  (usually  carbon  filament)  are  mounted 
close  to  these  reflecting  surfaces  and  the  patient  re- 
ceives the  beneficial  effect  of  the  actinic  light  rays  as 
well  as  of  the  heat  produced  by  the  lights  surrounding 
him.  The  wood  and  steel  cabinets  are  generally  lined 
with  mirrors,  whereas  marble  acts  as  the  reflecting 
surface  where  it  is  used.  The  patient's  head  is  always 
allowed  to  protrude  from  the  cabinet  and  he  is  never 
forced  to  breathe  the  hot  air  contaminated  by  the  toxic 


GENERAL     APPLICATIONS  223 

emanations  of  his  person,  which  is  unavoidable  in 
the  hot  air  and  steam  rooms. 

The  marble  cabinet  shown  in  the  illustration  is 
made  l)y  James  B.  Clow  &  Sons.  It  is  lined  with  56 
sixty-watt  car'bon  lights  and  has  a  total  capacity  of 
3360  watts  when  all  the  six  control  switches  are  closed. 
The  range  of  temperature  is  from  80  deg.  to  180 
deg.  F.  From  3  to  10  minutes  is  required  to  bring 
out  a  sweat  and  the  average  duration  of  the  bath  is 
from  12  to  20  minutes,  depending  upon  the  initial 
heating,  the  outside  temperature,  and  the  physical 
condition  of  the  patient. 

Beer  Vat  Dryer. — For  drying  out  vats  in  a  brew- 
ery during  the  varnishing  season,  the  General  Electric 
beer  vat  dryer  is  convenient  and  satisfactory.  It  is 
4  feet  long,  8^  inches  wide,  4  inches  high  and  is  fitted 


G.   E.   Beer  Vat  Dryer. 

with  six  500-watt  resistance  tubes  mounted  on  center 
and  end  castings.  The  ends  and  sides  are  of  sheet 
metal,  and  the  top  and  bottom  of  galvanized  wire 
mesh.  It  is  claimed  by  the  manufacturers  that  one 
of  these  devices  will  dry  out  a  50-barrel  vat  in  about 
10  hours.  Two  heaters  are  recommended  for  a  150- 
barrel  vat,  and  three  for  a  350-barrel  vat. 

Branding  Irons. — A  large  number  of  special  elec- 
trically heated  branding  irons  are  in  use.  They  are 
ideal  for  branding  wood,  leather,  meats,  etc. 

Button  Die  Heater. — Electrically  heated  dies  have 
been  used  for  some  time  in  the  manufacture  of  cellu- 


C.    H.    Heater   Applied    to    CeUuloid  Button  Die. 


224  ELECTRIC     HEATING 

loid  buttons.  These  devices  are  made  in  capacities  of 
from  60  to  150  watts,  and  are  usually  controlled  by 
rheostats  mounted  on  the  bed  plates.  A  number  of 
dies  may  be  mounted  on  one  head. 

Can  Capping  Machine  Heater. — An  application 
of  electric  soldering  iron  units  of  250  watt  capacity 
to  can  capping  machines  has  been  designed  by  the 
General  Electric  Company.  Apparatus  operated  in 
this  manner  has  been  found  much  more  satisfactory 
than  gas  heated  equipment. 

Candy  Batch  Warmer.  —  The  electric  batch 
warmer  is  portable  and  has  a  swing  adjustment  so  that 
the  heat  can  be  thrown  in  different  directions  as  de- 
sired.    It   serves  the  same  purpose  as   the   open   gas 


C.  H.  Batch  Warmer. 


warmer,  but  has  certain  obvious  advantages  over  fuel 
apparatus. 

The   Cutler-Hammer   batch    warmer   is    made   in 
two  standard  sizes,  as  follows : 


Length  in  Inches, 

Watts. 

No.  Heats. 

24 

2500 

3 

48 

5000 

6 

Celluloid  Embossers. — A  method  of  attaching  25 
watt  and  38  watt  soldering  iron  units  to  the  embossing 
heads  on  the  lower  part  of  celluloid  embossing  presses 
has  been  developed  by  the  General  Electric  Company. 
The  electrically  heated  dies  are  ideal ;  a  maximum  tem- 
perature of  140°  F.  is  maintained ;  and  all  danger  from 
working  with  inflammable  material  is  obviated. 


GENERAL     APPLICATIONS 


22f 


Chocolate  Warmers. — For  maintaining  chocolate 
at  proper  temperature  for  dipping,  the  electrically 
heated  warmers  have  proved  their  superiority  on  ac- 
count of  the  accuracy  of  adjustment  possible  and  the 
cleanliness  and  convenience  afforded.  They  consist 
of  two  pans ;  an  inner  one  holding  the  chocolate  and 
an  outer  one  fitted  with  a  surface  heating  element. 

Chocolate  warmers  in  the  following  sizes  and  ca- 
pacities may  be  obtained  for  flush  mounting  on  dipping 
tables : 


C.  H.  Chocolate  Dipping-  Table  With  Warmer  and  Side  Pans. 


Rectangular  Chocolate  Warmers    (Cutler-Hammer). 
Quarts 


Capacity, 

Inside 

Dimensions 

in  Ins. 

—Watts- 

2/3  Full. 

Length. 

Width. 

Depth. 

High.    Medium. 

Low 

4 

12  3/16 

6  3/16 

5 

180              90 

45 

6 

14  1/16 

7  5/16 

5% 

220            110 

5& 

10 

141/2 

10 

7 

310            155 

77 

12 

20 

12 

51/2 

375            188 

94 

Rectangrular    Tjpe    (Westi 

nghouse). 

4 

12 

61/2 

5 

220            110 

55 

Round   Type    Chocolate   Warmer    (Cutler-Hammer). 
Quarts. 
Capacity.  Inside  Dimensions,  Ins.  — Watts — 

2/3  Full.     Diameter.       Depth.  High.  Medium.        Low. 

4  9  6%  160  80  40 


ELECTRIC     HEATING 


Electrically  heated  side  pans  are  furnished  with 
the  Cutler-Hammer  rectangular  chocolate  warmers  in- 
stead of  marble  slabs.  Two  of  them  may  be  mounted 
on  opposite  sides  of  the  warmer.     They  are  made  in 


the  following  standard  sizes 


HEATER   RECEPTACLE         CONTROL  SWITCH      CHOCOLATE  PAN 

Westinghouse   Chocolate   Warmer. 

Heated  Side    Pans. 

Dimensions  in  Inches.  Watts. 

12"xl5"  25 

12"xl7"  29 

12"  X  221/2"  38 

Clothes  Dryers. — Where  fuel  cost  is  high  or 
where  operating  cost  is  relatively  unimportant  in  com- 
parison with  convenience,  electrically  heated  clothes 
dryers  are  desirable.  It  is  obvious  that  the  drying  of 
clothes  in  the  laundry  saves  time  and  eliminates  the 
many  disadvantages  of  hanging  out  the  washing  on 
the  old-fashioned  clothes  line. 

The  Chicago  electric  dryer  is  made  of  heavy  gauge 
galvanized  sheet  metal  with  single  casing,  double  cas- 
ing insulated  with  asbestos,  or  double  casing  insulated 
with  an  intervening  air  space.  The  panels  of  the  racks 
are  of  similar  material.  The  rear  panels  are  provided 
with  extension  plates,  so  that  when  the  racks  are 
pulled  out,  the  heat  will  not  escape  from  the  machine. 
The  brackets  are  of  cast  iron,  and  the  hanging  bars  are 
of  galvanized  pipe.  The  sheave  wheels  are  run  on 
ball  bearings.  The  base  of  the  cabinet  below  the 
racks  is  provided  with  galvanized  wire  screen  for  the 
protection  of  clothes  that  might  fall  from  the  racks. 

The  electrically  heated  dryers  are  made  in  four 
standard  sizes  for  use  on  110  or  220  volt  circuits. 

Lineal  Ft. 

Dryer            Outside  Dimensions.  No.    Hanging  Kw.  Ca- 

Number.  Height.  Length.    Width.  Racks.  Capacity  pacity. 

E  29               7'               7'               2'     1"  2                 78  3 

E39              7'               7'               2' 10"  3               117  4.5 

E49               7'               7'              3'    7"  4               156  6 

E59               7'              7'               4'     4"  5               195  7.5 


GENERAL     APPLICATIONS  227 

Corn  Popping  Machines. — An  electric  corn  pop- 
per of  1500  watts  heater  capacity  and  operated  with  a 
one-sixth  horsepower  motor  is  now  available.  It  is 
similar  to  those  seen  in  public  places,  and  has  a  ca- 
pacity of  about  60  bags  of  popcorn  per  hour. 

Corset  Irons. — The  Simplex  corset  iron  is  made  in 
an  8^  pound,  500  watt  size.  It  may  be  obtained 
with  either  a  hand  or  an  automatic  regulator  or  a  com- 
bination of  both. 

Drying  Ovens. — Specially  constructed  ovens  are 
used  for  drying  lumber,  for  removing  moisture  in 
photogravure  work,  for  drying  leather  boxes  and 
traveling  bag  parts  that  have  been  glued,  and  for  re- 
moving the  moisture  from  bottles  and  cans  before 
filling  with  powders. 

Embossing  Press  Heaters. — Any  gas  or  steam 
heated  embossing  head  may  be  easily  fitted  with  electric 
heaters  and  higher  operating  efficiencies  insured.  They 
may  be  heated  quickly  (usually  from  ten  to  fifteen 
minutes),  and  afiford  a  sensitive  and  uniform  temper- 
ature over  the  entire  surface.  Simplex  embossing 
press  heaters  have  been  made  in  a  great  variety  of 
sizes  and  capacities.  They  are  usually  made  to  order 
on  account  of  the  great  variety  of  press  heads  in  use. 
The  heaters  are  fiat  discs  about  one  inch  thick.  They 
are  bolted  to  the  press  head  and  the  embossing  dies 
placed  over  them.  They  may  be  made  in  two  or  more 
sections,  so  that  portions  only  of  the  head  may  be 
heated,  if  desired. 

Cutler-Hammer  press  heads  and  press  blocks  are 
also  manufactured  in  a  variety  of  sizes  and  capacities 
for  industrial  use. 

The  following  information  is  usually  required  for 
making  up  a  design  of  press  heater: 

(1)  Nature  of  work  to  be  done. 

(2)  Speed  of  operation. 

(3)  Temperature  required. 

(4)  Pressure  to  be  applied. 

(5)  Dimensions  of  dies  and  manner  applied. 

(6)  Sketch  showing  dimensions  of  press  head. 


228 


ELECTRIC     HEATING 


Sheridan    No.    8D    Press    Equipped   With    46  in.  x  33  in. 
Press  Head. 

Engraver's  Stoves. — Three-heat  stoves  of  600 
watts  capacity  are  being-  used  successfully  for  heating 
engraved  plates  during  the  inking  process. 

Envelope  Gum  Dryer. — With  a  500  watt  heating 
unit  fitted  in  the  blower  cabinet,  the  capacity  of  a 
machine  will  be  increased  about  100  per  cent. 

Fan  Drying  Equipment. — A  small  dryer  of  1000 
watts  capacity,  which  is  attachable  to  a  standard  fan 
motor,  has  been  developed  by  the  General  Electric 
Company.     It  has  a  wide  field  for  application  in  pho- 


GENERAL     APPLICATIONS 


229 


C.  H.  Engraver's  Stove. 


tographic  studios  for  drying  prints  and  negatives.  The 
heating  coils  are  mounted  vertically  in  an  aluminum 
frame  and  covered  with  a  screen  guard. 


Motion  Picture  Film   Dryer. 


I 


Film  Dryers. — A  large  motion  picture  studio  has 
developed  a  film  drying  oven,  consisting  of  an  outside 
casing,  within  which  a  large  ribbed  cylindrical  reel, 


230  ELECTRIC     HEATING 

similar  to  a  ferryboat  paddle  wheel,  is  mounted.  The 
oven  is  heated  with  four  3000  watt  G.  E.  beer  vat 
dryers  mounted  around  the  sides.  The  film  is  wound 
on  the  outside  of  the  reel.  The  drying  process  com- 
pletes work  in  30  minutes  that  formerly  required  10 
hours'  time,  and  much  better  results  are  obtained. 


E.  &  A.  Type  FW  Laboratory  Flask  Heater. 

Flask  Heaters. — A  flask  heater  for  laboratory  use 
is  very  convenient.  It  is  made  of  copper  with  a  con- 
centric ring  top.  The  small  size  is  8^x4  inches  deep, 
and  consumes  500  watts  at  maximum  heat. 

Gilding  Wheel  Heaters. — These  devices  are  used 
for  bookbinding,  and  are  convenient  on  account  of  the 
absence  of  soot  and  dust  and  the  concentrated  heat 
afforded.  They  are  fitted  with  heaters  which  revolve 
on  roller  bearings.  Ordinary  dies  may  be  used  with 
these  heaters  by  turning  a  recess  on  one  side  and  drill- 
ing holes  for  the  clamping  studs.  Simplex  gilding 
wheel  heaters  are  made  in  the  following  sizes  and  ca- 
pacities : 

77  watt  heater,  3  19/32"  diameter,  21"  long. 
85  watt  heater,  4"  diameter,  21"  long-. 

A  rheostat  may  be  supplied  with  the  larger  size 
for  finer  temperature  adjustment. 

Glove    Stretchers    and    Laying-off    Boards. — The 

electrically  heated  glove  stretchers  and  laying-off 
boards  manufactured  by  the  C.  L.  McBride  Manufac- 
turing Company  are  ideal  for  the  dry  cleaner  and  glove 
manufacturer.  The  stretchers  are  superior  to  the  or- 
dinary steam  heated  devices.  Steam  laying-off  boards 
are  not  flexible ;  will  not  give  to  allow  the  gloves  to  be 


GENERAL     APPLICATIONS 


231 


fitted,  and  consequently  require  more  time  to  adjust 
the  glove  fingers.  The  heat  also  varies  with  the  pres- 
sure, and  the  quality  of  the  work  is  not  uniform.  These 
disadvantages  are  overcome  in  the  electric  glove 
stretcher.  The  temperature  is  regulated  by  a  thermo- 
stat. It  is  mounted  on  a  revolving  base.  The  quality 
of  the  work  is  better,  and  may  be  done  more  rapidly 
and  with  less  skilled  labor  than  where  steam  is  used. 
Only  a  relatively  few  forms  are  required,  because  each 
stretcher  will  make  four  full  sizes  of  gloves  from  one 
form. 

The  electrically  heated  laying-oi¥  boards  are  made 
for  finishing  dry  cleaned  gloves,  and  may  be  used  in 
a  kid  glove  factory  although  they  are  too  light  for 
heavy  gloves.  They  are  much  cleaner  and  safer  and 
will  turn  out  more  and  better  work  than  steam  boards. 

Glue  Pots. — Electrically  heated  glue  pots  elimi- 
nate soot,  smoke,  and  flame;  do  away  with  steam  and 
gas  pipes;  are  readily  moved  from  place  to  place,  and 
insure  even  temperature  regulation.  They  are  manu- 
factured both  with  and  without  water  jackets. 

The  relative  sizes  and  capacities  of  glue  pots  made 
by  three  prominent  manufacturers  are  as  follows : 


Westinghous" 

Cast    Iron    Glue 

Pot. 


Simplex  No.  40S 
Glue  Pot. 


General    Electric 
Glue    Pot. 


Pot 

Make.  Capacity. 

Gen.    Electric.  ..1/^  pt.  to    8  qt, 

Gen.    Electric...   1  pt.  to    4  qt. 

Westinghouse..    1  pt.  to    4  qt. 

Simplex     1  pt.  to    2  qt. 

Simplex     1  pt.  to  20  qt. 

American     2  pt.  to    4  qt. 


Small.       Large. 
Low.  High.  Low.  High. 

20  250  jacketless 

85   340   275  1100  jacketed 

55   200   200      660  jacketed 

110  440   220     880  jacketless 

85  330   625   2500  jacketed 

125   500  250  1000  jacketed 


1-heat 
3 -heat 
3-heat 
3-heat 
3-heat 
3-heat 


232  ELECTRIC     HEATING 

Glue  Cookers. — Quantities  of  glue  may  be  heated 
in  large  pots  and  transferred  to  small  pots  for  use  in 
various  parts  of  an  establishment.  The  cookers  are 
usually  heavily   insulated  against  heat  losses. 


1 

•  ■■•  ■  1 

! 
i 

T  "  ]  ^  ^ ,  "T"'" 

! 

!> 

i 

1/-— — \J 

Section  of  a  Westinghouse 
Glue    Cooker. 


Tabular  specifications  of  standard  Westinghouse 
glue  cookers  are  as  follows : 


Gallons 

V^atts 

Input. 

No.  of 

Capacity. 

Starting. 

Running-. 

Heats. 

3 

1800 

450 

2 

5 

2200 

550 

2 

10 

2700 

675 

2 

15 

6000 

750 

5 

20 

6600 

825 

5 

25 

7200 

900 

5 

The    following    data    refer    to    standard    General 
Electric  glue  cookers : 


Gallons 

V7atts 

Input. 

Av. 

Hr.  Time 

Floor  Space 

Capacity. 

Starting. 

Running. 

to  attain  165° 

F.     in  feet. 

20 

10,500 

450 

1 

3i4x3y4 

35 

14,000 

5i00 

ly* 

31/2x8^ 

50 

16,500 

600 

1^ 

3%x3% 

80 

20,000 

700 

1% 

4     x4 

140 

26,500 

850 

2 

4y2x4% 

220 

32,aoo 

1,050 

2y2 

5     x5 

Gold  Leaf  Stamp  Heaters. — These  devices  may  be 
used  in  place  of  gas  for  stamping  gold  leaf  on  combs, 
pipes,  neckwear,  etc.  A  Simplex  die  heater  consuming 
80  watts  has  been  designed  to  fit  a  standard  pencil 
stamping  machine  for  imprinting  gold  leaf  letters. 


GENERAL     APPLICATIONS  233 

Hatters'  Flanging  Bags. — Electrically  heated 
flanging  bags  are  superior  in  every  way  to  bags  heated 
over  steam  bake  ovens.  The  heat  is  constantly  gen- 
erated within  the  bag;  the  thermal  efficiency  is  greater ; 
the  temperature  is  more  uniform ;  and  no  time  is  lost 


C.    11.    I'langing-    Uag'. 

in  reheating.  Hats  may  be  flanged  in  less  time  and 
with  better  and  more  uniform  results.  The  Cutler- 
Hammer  flanging  bags  consume  440  watts,  and  are 
furnished  with  a  metal  pan  fitted  with  lifting  ears. 
The  sand,  lifting  tackle  and  canton  flannel  covering  are 
provided  by  the  user. 

Hatters'  Hand  Flats. — Four  faces  of  the  straw  hat- 
ters' hand  flats  are  working  surfaces.  Three  standard 
styles  are  made  by  the  Cutler-Hammer  Company.  The 
hand  flat  is  mounted  on  a  support,  and  may  be  used 
in  any  desired  position.  Cleanliness  is  essential  in  the 
manufacture  of  straw  hats,  and  the  clean,  uniform 
heat  supplied  by  the  electric  hand  flat  makes  for  in- 
creased speed  and  perfection  of  product.  The  energy 
required  for  these  devices  varies  from  550  to  700  watts, 
depending  upon  the  style  of  hand  flat  used. 

Hatters'  Hand  Shell. — The  Cutler-Hammer  hat- 
ters' hand  shells  conform  in  shape  to  the  old-fashioned 
shells.  The  body  of  the  shell  is  a  single  casting,  and 
can  be  dipped  in  water  for  cooling  the  faces  of  the  iron. 
These  irons  are  made  in  the  following  standard  weights 
and  capacities : 


234  ELECTRIC     HEATING 

Weight  in  Pounds. 


10 1^ 

12 

15 


Watts. 
300  or  350 
300  or  350 
350  or  500 
350  or  500 


Simplex  hatters'  irons  are  made  in  9  and  15  pound 
sizes,  and  with  450  watts  capacity  each.  They  may  be 
provided  with  plain  or  automatic  regulators. 


C.   H.   Hand  Shell,   Hand   Flat  and  Velouring-  Stove. 

Hatters'  Velouring  Stove. — The  Cutler-Hammer 
velouring  stove  is  encased  in  a  heavy  cast  iron  frame 
with  tight  joints  to  prevent  particles  of  felt  from  lodg- 
ing in  the  crevices.  They  are  made  in  the  following 
standard  sizes  for  either  single  or  two-heats : 


Size  of  Top, 

Watts  Capacity 

in  Inches. 

Single-Heat. 

Two-Heat. 

4y2x6 

315 

315-475 

514x7 

450 

450-675 

Doran    Machine    Iron  Nos.    1   and   2. 


Hatters'  Machine  Irons. — Irons  for  use  on  hatters' 
machines  are  more  satisfactory,  more  economical,  and 
result  in  better  work  and  greater  output  than  other 
such  appliances.     Gas  heated  machine  irons,  equipped 


GENERAL     APPLICATIONS  235 

with  gas  and  air-blast  tubes,  soon  develop  loose  con- 
nections, create  dangerous  hot  spots,  and  do  not  main- 
tain a  uniform  heat. 


Tweedy    Right    Hand    CurHng   Machine    Iron. 

Cutler-Hammer  irons  are  made  for  the  following 
hat  blocking  and  curling  machines : 

Watts. 

Doran   Machine   Iron    No.    1 300 

Doran    Machine    Iron    No.    2 30i0 

Doran    Machine    Iron    No.    3 275 

Newark  Machine   Iron 400 

Tweedy  Right  Hand  Curling  Iron 750 

Tweedy   Left   Hand    Curling   Iron 750 

Hot  Air  Blower. — A  25  kilowatt  General  Electric 
hot  air  blower  fitted  with  152  ribbon  wound  flat  heat- 
ing units  and  a  blower  fan  has  been  found  useful  for 
drying  transformers  and  other  similar  operations.  The 
volume  and  temperature  of  the  air  supplied  naturally 
depends  upon  the  size  and  speed  of  the  fan. 

Industrial  Heating  Units. — In  order  to  avoid  de- 
signing and  manufacturing  special  heating  units  for 
each  industrial  application  that  is  presented,  the 
General  Electric  Company  has  standardized  on  three 
types  of  units,  one  or  more  of  which  are  adaptable  to 
the  usual  conditions  that  are  met.  These  units  are 
known  as  cartridge,  flat  leaf,  and  tubular  type  units. 

Cartridge  units  are  made  in  various  capacities  up 
to  750  watts,  and  in  sizes  up  to  1^  inch  diameter  and 
8  inch  length.  These  units  operate  at  a  dull  red  heat. 
They  are  usually  fitted -into  drilled  holes  in  castings 
and  bolted  to  the  body  to  be  heated.     They  consist  of 


236 


ELECTRIC     HEATING 


Westing-house    Narrow    Type 
Industrial    Heater. 


Westing-house     Wide     Type 
Industrial   Heater. 


resistance  ribbons  wound  edgewise,  cemented  and 
sealed  inside  of  metallic  tubing. 

Flat  leaf  units  are  used  for  heating  flat  surfaces. 
They  are  made  in  capacities  of  300  watts  or  less  and 
with  dimensions  of  6  inches  by  2  inches  by  }i  inch. 
They  consist  of  resistance  ribbons  wound  on  mica 
sheets  and  clamped  between  iron  protecting  plates.  Any 
desired  number  of  these  units  may  be  bolted  to  the 
surface  of  any  smooth,  flat  surface  to  be  heated. 

Tubular  type  units  are  used  for  air  heating  and 
are   made   for  low  temperature   work.     The   standard 


N/r  No  I 


Htr  No  Z 


Heater 
Terminals 


I 
To        7. 


J-Heat  Heaters 


Htr  No  I  Htr  No  2  Htr  No  3  Htr  No  4 

neater    \ 
Terminols\ 


I -Heat  Heaters 


To  Line 


To  Line 


3-HeatSnapSii/itch 


Higt) 


tl  J 


r 


To  Heaters 
Two-Heat  f(nife  Switch. 
Diagram    for    Connecting   Two    Single    Heat   Heaters    or 
Multiples  Thereof  for  Three  Heat  Control. 


GENERAL     APPLICATIONS  237 

size  is  2  in.  in  diameter  and  22  in.  long,  and  dissipates 
about  350  watts.  It  consists  of  resistance  wire  wound 
on  an  asbestos  tube  and  coated  with  a  stiffening  of 
insulating  compound. 

The  Westinghouse  Company  has  recently  devel- 
oped a  very  complete  line  of  ''steelclad"  heating  units 
for  industrial  purposes.  They  consist  of  flat  ribbon 
resistors  assembled  on  mica  sheets  covered  with  steel 
casings,  and  provided  with  suitable  terminals.  They 
are  made  in  the  form  of  bayonets  with  single  or  three 
heat  control,  in  lengths  varying  from  10  in.  to  50  in. 
The  narrow  type  is  j/g  in.  thick  and  1%  in.  wide,  and 
the  wide  type  3/16  in.  thick  and  2%.  in.  wide.  The 
wattage  of  these  units  may  be  calculated  from  the  fol- 
lowing table : 

Maximum  Watts  per  Inch  of  Length. 
Class.  Wide  Type.     Narrow  Type. 

A     (Ovens   and   drying-   rooms) 15  7.5 

B      (Ordinary   Air  Heating)    30  15 

C     (Pressheads,  hot  plates,  etc 50  25 

Ironing  Machines. — Laundry  machines  of  all  kinds 
may  be  equipped  with  electric  heaters.  They  insure 
a  clean,  sanitary,  cool  laundry,  and  result  in  producing 
more  and  better  work.  An  example  of  an  application 
of  electric  heat  in  the  laundry  is  that  of  the  American 
Iron  Machine  Company's  ''Simplex  Ironer,"  which  is 
made  in  the  following  sizes  and  capacities : 

Simplex  Ironers. 

Length    of   roll    in   inches.    24        26        32  37  42  46       48  56 

Diam.   of  roll   in   inches..      6  7  7  7  7  7       8.5  8.5 

Ironing  shoe  face  in    inches    58888899 

Ironing  shoe  contact,  ins.  .     2.5       5  5  5  5  5       6  6 

Ironing  speed  ft.  per  min.     6.5       7  7  7  7  7       8.5  8.5 

Kw.    capacity — high 1.85    2  2.5  3  4  4.8   5  6 

Kw.    capacity— medium.  .  .     1.25     1.3       1.7  2  2.7       3.2   3.4  4 

Kw.    capacity— low 60       .75       .85  1  1.3       1.6   1.7  2 

Size   of  motor   in   hp 1-10      1-8      1-8  1-8  1-6  1-6   1-4  1-4 

Laboratory  Hot  Plates. — The  uniform,  depend- 
able and  safe  heat  obtainable  from  electric  hot  plates 
and  stoves  make  them  most  desirable. 


Simplex  4i^   in.  by  24  in.  Laboratory  Hot  Plate, 


238  ELECTRIC     HEATING 

Rectangular  Simplex  hot  plates  of  the  following 
dimensions  and  capacities  are  available  for  securing 
various  temperatures : 


6"  X  6" 

500  watt 

three-heat 

6"xl2" 

750  watt 

three-heat 

2%"x  24" 

500  watt 

three-heat 

41/2"  X  24" 

600  watt 

three-heat 

3"x6" 

200  watt 

three-heat 

6"x6" 

350  watt 

three-heat 

Small,  round  Simplex  discs  in  sets  of  six  mounted 
on  slate  bases  are  convenient  for  milk  testing  and  other 
laboratory  operations. 

6-  31/^"  discs  total     &00  watts  single-heat. 

6-  4%"  discs  total  1500  watts  single  or  three-heat. 

Laundry  and  Tailors'  Irons. — The  conditions  un- 
der which  these  irons  are  used  are  vastly  different  than 
those  in  the  home.     They  are  usually  subject  to  rough. 


Simplex    No.    1540   Drag   Iron. 

careless  handling,  and  severe  long  hour  use.  They 
must  be  heavily  and  durably  constructed  to  meet  ordi- 
nary requirements. 

A  large  variety  of  irons  are  available  for  industrial 
use.  Pointed  and  round  nose,  smoothing  and  finishing- 
irons  are  manufactured  in  many  sizes.  Those  made 
for  laundry  work  usually  vary  in  weight  from  four  to 
twelve  pounds  and  consume  from  275  to  750  watts. 
Drag  irons  are  made  in  weights  of  from  30  to  50 
pounds  and  wattages  of  from  1400  to  1600  watts.  Puff 
irons  in  egg  and  half  egg  shapes  are  made  in  capacities 
of  from  150  to  400  watts. 

Tailors'  irons  usually  vary  from  12  to  25  pounds 
in  weight  and  from  600  to  900  watts  in  capacity.  They 
are  made  with  diamond,  oval,  and  special  broad  noses. 
Simplex  irons  of  various  sizes  and  shapes  are  made 
for  use  in  pressing  machines. 


GENERAL     APPLICATIONS 


239 


Westinghouse,  American,  Cutler-Hammer,  Gen- 
eral Electric  and  Simplex  laundry  and  tailors'  irons 
are  manufactured  in  a  variety  of  types,  shapes  and 
sizes. 


C.    IL   Tailor's    Jr.. 


Leather  Creasing  Tool. — A  recently  developed  de- 
vice for  branding  designs,  ruling  parallel  lines,  and 
edge  finishing  leather  articles  has  been  found  very  use- 
ful. The  tool  is  designed  on  the  principle  of  a  solder- 
ing iron  and  differs  only  in  the  tip  and  handle. 

Linotype  and  Monotype  Pots.  —  Among  the 
numerous  advantages  gained  by  the  application  of 
electric  heat  to  type  metal  pots  are  rapid  heating,  per- 
fect temperature  regulation,  absence  of  gas  fumes, 
smoke  and  soot,  elimination  of  excessive  room  tem- 
perature, ideal  working  conditions,  no  burning  out  of 
the  tin  of  the  metal  mixture,  and  production  of  solid, 
sharp  slugs. 

The  Cutler-Hammer  pots  are  equipped  with  im- 
mersion heaters,  heavy  thermal  insulation,  and  auto- 
matic temperature  control.  The  latter  consists  of  a 
dynamic  thermometer  and  a  magnetic  switch  panel. 
Expansion  or  contraction  of  mercury  in  the  thermom- 
eter actuates  a  relay  which  in  turn  operates  the  mag- 
netic switch,  cutting  the  current  in  the  heating  ele- 
ments on  or  ofif. 

It  maintains  a  temperature  of  approximately 
550°  F.    in   the   type   metal.     Initial   heating   requires 


240 


KLECTRIC     HEATING 


C.   H.   Linotype   Pot. 

1600  watts,  for  about  50  minutes  after  which  550  watts 
is  sufficient  to  maintain  the  temperature  when  100 
slugs  are  being  cast  per  hour. 


G.   E.   Monotype  Pot. 


The  General  Electric  pots  are  usually  equipped 
with  standard  cartridge  units.  Regulation  of  the  hear 
is  obtained  by  means  of  a  hand  operated  rheostat.  For 
heating  a  linotype  pot  holding  40  pounds  of  metal  a 


GENERAL     APPLICATIONS  241 

maximum  capacity  of  2250  watts  is  provided.  To 
maintain  working  temperature  using  8  pounds  of  metai 
per  hour  750  watts  is  required.  P'or  heating  the  same 
weight  of  metal  in  a  monotype  pot  2900  watts  is  pro- 
vided, and  for  maintaining  the  proper  temperature, 
using  16  pounds  of  metal  per  hour,  2400  watts  is  re- 
quired. 

Liquid  Heating  Tanks. — Manufacturing  processes 
that  require  the  use  of  hot  liquids  for  dipping  purposes 
may  often  utilize  electrically  heated  tanks  to  advan- 
tage, especially  where  the  solution  is  of  an  inflam- 
mable or  explosive  nature.  The  vessels  are  usually 
well  lagged  and  fitted  with  covers. 

Tanks  of  the  following  dimensions  and  capacities 
are  made  for  heating  liquids  by  the  General  Electric 
Com  pan  v: 


Average  Hours 

Capacity 

Required 

in 

Total 

Outside 

Dimensions. 

for  Heating 

Gallons. 

Kilowatts. 

Diameter. 

Height. 

Oils  to  212°  F. 

40 

16.5 

27" 

25" 

1.3 

60 

22.5 

31" 

29" 

1.4 

85 

30 

35" 

31" 

1.5 

125 

39 

39" 

35" 

1.7 

200 

52.5 

46" 

40" 

2 

300 

58.5 

54" 

45" 

2.7 

500 

67.5 

62" 

55.5" 

3.9 

750 

75 

70" 

62.5" 

5.3 

1000 

79.5 

76" 

68.5" 

6.7 

I 


r 


Matrix  Dryers. — The  most  important  factors  to 
be  considered  in  matrix  drying  are  quality  of  the  mat, 
cost  of  drying  and  speed  of  drying.  The  temperature 
usually  required  for  this  work  is  from  350°  to  400°  F. 
The  common  methods  of  drying  are  accomplished  by 
the  use  of  either  gas  or  steam  heat.  In  addition  to 
the  many  obvious  disadvantages  of  gas  heated  ap- 
paratus, it  does  not  provide  the  uniform  temperature 
that  is  so  desirable  for  this  class  of  work.  Steam 
heated  dryers,  on  the  other  hand,  supply  a  uniform 
heat,  but  unless  excessively  high  pressures  are  avail- 
able the  operating  temperatures  are  too  low  for  quick 
work. 

Electrically  heated  matrix  dryers  have  overcome 
all  the  undesirable  features  of  other  apparatus.  The 
heat  is  clean,  safe,  dependable,  and  automatically  regu- 
lated  to  provide  the  desired  operating  temperatures, 


242 


ELECTRIC     HEATING 


f 


C.   H.  Matrix   Machine   Heater. 


and  it  does  away  with  the  maintenance  of  troublesome 
and   costly   equipment. 

Cutler-Hammer  matrix  dryers  are  manufactured 
complete,  ready  to  slip  into  the  bed  of  the  machine. 


G.   E.   Matrix  Drying   Press. 


The  temperature  is  regulated  by  the  pressure  of  satu- 
rated steam  generated  in  a  tube  cast  into  the  heater 
and  attached  to  a  contactor  pressure  gauge,  which  in 


GENERAL     APPLICATIONS  243 

turn  actuates  a  magnetic  switch,  cutting  the  current 
on  and  off.  The  dryer  is  also  fitted  with  pilot  lamps 
to  indicate  when  energy  is  being  consumed. 

General  Electric  matrix  dryers  are  also  automat- 
ically controlled.  The  standard  size  is  rated  at  28 
kilowatts,  and  is  applied  intermittently  by  the  auto- 
matic regulator.  It  is  claimed  by  the  manufacturers 
that  these  dryers  will  consume  about  one  kilowatt  per 
hour  per  mat. 

Meat  Brander. — This  device  is  used  for  inspection 
stamps  and  is  legible  at  end  of  curing  process.  A  ham 
branding  die  made  by  the  General  Electric  Company 
consists  of  a  21  pound  block  of  cast  iron  heated  with 
two  600  watt  cartridge  units.  The  branding  die  is  of 
cast  brass  inserted  in  the  top  of  the  body  casting. 
After  initial  heating,  low  heat  is  maintained.  Each 
ham  is  branded  by  placing  it  on  top  of  the  heated  die 
for  from  3  to  4  seconds. 

Metal  Melting  Tanks. — For  bringing  tin,  lead, 
solder,  babbitt  metal  and  various  alloys  to  the  melting 
point,  electrically  heated  tanks  can  often  be  used  to 
advantage,  especially  where  it  is  desirable  to  secure 
accurate  temperature  adjustment.  These  tanks  should 
be  heavily  constructed  and  provided  with  efficient 
thermal  insulation. 

Tanks  of  the  following  sizes  and  capacities  are 
manufactured  by  the  General  Electric  Company : 


Capacity 

80% 

Full. 

Lbs. 

.Lbs. 

Inside  of  Tank   (inch 

es). 

Watts 

Lead. 

Tin. 

Diam. 

Length. 

Width. 

Depth. 

Capacity 

30 

19 

4%" 

5y2" 

2,100 

50 

30 

5%" 

evz" 

2,400 

75 

45 

eva" 

6%" 

3,000 

10(0 

60 

7" 

TVs" 

3,900 

2>00 

125 

9" 

9V2" 

4.550 

300 

190 

10" 

11%" 

6,500 

400 

250 

11" 

12%" 

8,450 

560 

360 

15" 

13" 

9" 

13,000 

80(0 

520 

15" 

13" 

13" 

15,600 

1080 

690 

20" 

13" 

13" 

17,500 

1230 

860 

20" 

16" 

13" 

22,1(00 

1640 

1050 

20" 

16" 

16" 

22,800 

2060 

1275 

25" 

16" 

16" 

26,000 

2330 

1600 

30" 

16" 

16" 

28,600 

2960 

1900 

30" 

19" 

16" 

30,0(00 

It  is  claimed  that  a  3000  watt  pot  will  melt  approx- 
imately 52  pounds  of  alloy  consisting  of  18  parts  anti- 


244 


ELECTRIC     HEATING 


mony,  20  parts  tin,  and  100  parts  lead  in  one  hour. 
Medium  heat  will  perform  the  same  operation  in  3 
hours. 

Cutler-Hammer  type  metal  crucibles  arc  made 
with  external  or  immersion  heaters  in  sizes  of  from 
.SO  pounds  to  500  pounds  capacity. 


G.  E.  Metal  Melting  Tank. 


Number  Brander. — This  recently  developed  de- 
vice consists  of  an  electrically  heated  circular  plate, 
on  the  outside  of  which  is  mounted  a  small  wheel  bear- 
in  ^^  in.  figures  reading  from  0  to  9. 


G.    E.   Oil    Tempering-   Bath 


Oil  Tempering  Baths. — Where  a  large  amount  of 
tool  tempering  is  done  the  electric  oil  bath  is  indis- 
pensable. Uniform  temperature  control  is  attained, 
and  fire  hazard,  uncertainty,  and  harmful  oxidation  of 
the  metals  is  eliminated  in  this  process.  The  work 
may  be  done  successfully  with  unskilled  labor  because 
the  temper  is  drawn  by  the  submersion  process. 


GENERAL     APPLICATIONS 


245 


General  Electric  oil  tempering  baths  furnished 
with  or  without  cooling  coils  and  controlling  panels  are 
made  in  the  following  standard  sizes  and  capacities : 

Oil  Capacity  Dimensions  in  Inches.  Maximum 

Gallons.  Length.  Width.  Depth.  Kilowatts. 

9  22  12  8  6 

11  18  12  12  7.2 

37  30  16  18  20 

The  drawing  temperature  of  different  grades  of 
steel  varies  from  300°  to  320°  F.  The  20  kilowatt  size 
bath  is  said  to  have  drawn  the  temper  of  363  pounds 
of  steel  ball  bearings  in  1  hour  and  45  minutes  with 
a  total  energy  consumption  of  9.5  kilowatt  hours. 

These  baths  are  being  used  successfully  for  melt- 
ing rosin  compounds  required  in  the  manufacture  of 
shrapnel  shells.  They  may  be  used  equally  as  well 
for  heating  and  melting  many  other  compounds. 


C.   H.   Pallette   Heater. 

Pallette  Die  Heaters. — In  book  binding  establish- 
ments these  devices  have  a  number  of  advantages  be- 
cause of  the  concentrated  heat,  freedom  from  dust  and 
soot,  and  better  working  conditions  brought  about. 

The  Simplex  standard  machine  die  heater  is  of  140 
watts  capacity,  and  fitted  with  rheostat  and  flexible 
cord.     It  is  provided  with  a  triangular  piece  of  metal 


246 


ELECTRIC     HEATING 


across  the  back  for  fastening  in  the  head  of  the  ma- 
chine. The  rectangular  pocket  for  the  dies  is  1>4  in. 
X  2^  in.  X  5/^  in.  deep.  The  hand  die  heater  is  of  135 
watts  capacity.  The  groove  for  the  die  is  ^  in.  x  5  in. 
X  i^  in.  deep.  The  length  of  the  device  including  the 
handle  is  9^2  in. 

Paper  Seal  Moistener. — Electric  heat  has  been 
found  convenient  for  heating  water  in  the  small  paper 
seal  moisteners  used  in  sealing  packages  and  cartons. 


Paper   Seal   Moistener. 

A  small  30  watt  heating  unit  immersed  in  a  container 
4  in.  X  6  in.  x  2  in.  deep,  will  raise  the  temperature  a 
sufficient  amount. 

Paper  Warmer. — In  order  to  do  away  with  the 
sticking  effect  produced  by  static  electricity  General 
Electric  tubular  heaters  have  been  placed  under  the 
paper  of  large  printing  presses  and  satisfactory  re- 
sults obtained. 

Peanut  Roasters. — Wm.  B.  Berry  &  Company 
has  developed  a  line  of  electrically  heated  and  operated 
peanut  roasters.  They  are  built  in  standard  sizes  of  16, 
24,  and  32  quart  capacities,  and  in  a  number  of  designs. 
The  latter  is  equipped  with  1.2  kw.  in  heating  units 
and  will  roast  about  one  bushel  of  peanuts  per  hour. 
The  manufacturers  claim  the  machines  have  been  used 
successfully  for  roasting  coffee  as  well  as  peanuts. 

Perforator  for  Drawings. — A  recently  developed 
heating  device  which  makes  minute  perforations  may 
be  run  over  a  drawing  and  the  pattern  used  for  a 
stencil. 


GENERAL     APPLICATIONS  247 

Photographic  Drying  Oven. — An  unlagged  galvan- 
ized iron  oven  5  ft.  long,  30  in.  wide,  and  30  in.  high, 
fitted  with  two  500  watt  General  Electric  tubular  type 
heaters  mounted  2  in.  from  the  floor  is  said  to  dry  pho- 
tographic prints  in  from  30  to  45  minutes,  whereas 
from  3  to  4  hours  was  formerly  required  for  drying 
them  on  blotting  paper  in  the  open  air.  Ventilation  is 
provided  by  a  6  in.  hole  in  the  bottom  and  a  small 
damper  in  the  top.  The  prints  are  placed  on  blotting 
paper  on  three  wire  mesh  shelves. 

Another  installation,  consisting  of  a  revolving  gal- 
vanized sheet  iron  drum  3  ft.  in  diameter  and  2  ft. 
wide,  heated  by  means  of  a  2000  watt  three-heat  Amer- 
ican radiator  inside  the  drum,  and  operated  by  means 
of  a  l/6th  horsepower  motor,  gave  very  quick  results. 
A  cloth  belt  passing  around  the  drum  and  over  rollers 
mounted  on  the  framework  permitted  the  wet  prints 
to  be  inserted  between  the  surface  of  the  drum  and  the 
cloth  belt.  The  warm  surface  of  the  drum  and  the  dry 
cloth  rapidly  remove  the  moisture. 

Pipe  Thawing  Outfits. — Portable  outfits  have 
proven  serviceable  for  thawing  frozen  pipes.  The  high 
tension  leads  are  connected  to  the  main  line  feeders 
and  the  low  tension  leads  are  attached  to  opposite  ends 
of  the  frozen  pipe  section.  In  residences  one  lead  is 
usually  attached  to  the  faucet  and  the  other  to  a  street 
hydrant.  Connections  may  be  made  to  two  hydrants 
when  street  mains  are  frozen,  or  excavations  may  be 
made  for  attaching  leads  direct  to  the  pipes. 

Pitch  Kettles. — Portable  devices  for  heating  pitch, 
varnishes,  oils,  etc.,  have  a  wide  range  of  application 
They  are  usually  provided  with  three-heat  control 
switches.  The  maximum  heat  is  used  for  heating  up 
the  substance,  medium  heat  for  stirring,  and  low  heat 
for  maintaining  a  constant  temperature. 

Simplex  pitch  kettles  have  the  following  dimen- 
sions and  capacities : 

12"  X    21/^"  deep       4  quart  1300  watts  maximum. 

15"  X    2y2"  deep       7  quart  1600  .watts  maximum. 

19"  X    9      "  deep      40  quart   3000  watts   maximum. 

30"xl4%"  deep  120  quart  7000  watts  maximum. 


248  ELECTRIC     HEATING 

Pleating  Machine  Heaters. — An  installation  for 
pleating  dress  goods,  made  by  the  General  Electric 
Company,  consisted  of  a  600  watt  heating  unit  fas- 
tened to  the  frame  so  as  to  project  inside  one  of  two 
7-inch  by  3-inch  corrugated  rollers,  and  a  temperature 
of  about  450°  F.  was  attained.  The  electric  heater 
was  substituted  for  a  gas  burner,  which  was  more  or 
less  dirty,  dangerous,  and  uncomfortable  to  work  over. 

Pouring  Pots. — Where  it  is  desired  to  keep  wax 
and  pitch  compounds  at  the  proper  consistency  for 
pouring,  General  Electric  portable  pots,  made  in  forms 
similar  to  its  jacketless  glue  pots,  are  useful. 

Printing  Ink  Heater. — In  order  to  keep  printing 
ink  warm  and  fluid  in  cold  weather,  a  small  heating 
unit  placed  beneath  the  ink  pad  has  produced  good 
results. 

Rectifier  Tube  Boiler. — For  lengthening  the  life 
of  rectifier  tubes  the  General  Electric  Company  has 
developed  a  means  of  boiling  the  tubes  in  water  for 
removing  the  carbon  deposits  on  the  inside  of  the 
glass.  A  copper  tank  29^  in.  long,  16^  in  deep,  and 
13  in.  wide,  lagged  with  asbestos  paper,  fitted  with 
a  tight  cover  and  heated  with  nine  1175  watt  cartridge 
units   constitutes   the   equipment. 

Roofing  Material  Vulcanizer. — This  application  of 
electric  heat  as  a  substitute  for  gas  heat  reduces  the 
unit  time  of  joining  rolls  of  rubber  roofing  paper  con- 
siderably. The  heating  units  consist  of  mica  insulated 
resistance  ribbon  clamped  between  iron  plates  (2  in. 
x6  in.  X  3/16  in.  thick).  These  350  watt  units  are  at- 
tached to  the  under  side  of  a  9  in.  x  60  in.  x  %  in.  thick 
iron  vulcanizing  plate,  and  a  temperature  of  about 
650°  F.  maintained.  Electric  operation  eliminates  gas 
fumes  and  fire  hazard,  and  is  far  more  convenient. 

Sealing  Wax  Pots. — For  applying  large  quantities 
of  sealing  wax,  an  electrically  heated  pot  is  more  con- 
''/enient  than  ordinary  stick  wax.  Special  Simplex  de- 
vices made  of  spun  copper  and  having  the  following 
capacities  are  in  use : 

Vz   pint     175   watt  maximum     4-heat. 
Wz    pint     300   watt   maximum      4-heat. 


GENERAL     APPLICATIONS 


249 


KSimplex  Sealing-  Wax  Pot. 

Shelf  Heaters. — Cutler-Hammer  electrically  heat- 
ed shelves  form  a  means  of  heating  ovens  already  built 
or  in  use.  The  shelves  form  separate  units,  which 
may  be  mounted  in  any  oven  of  similar  dimensions. 
They  are  suitable  for  use    in    incubators,  lacquering 


C.   H.   Self  Heater. 


ovens,  plate  warmers,  evaporating  and  drying  closets 
and  laboratory  cabinets.  The  shelves  are  of  perfor- 
ated sheet  metal,  mounted  on  iron  frame  work,  with 
the  heating  units  inside. 

The  standard  sizes  and  capacities  of  these  heaters 
are  as  follows : 


ngth. 

—Size  in  Inches 
Width. 

Th 

ickness. 

Maximum 
Watts. 

Number  of 
Heats. 

12 

6 

iy2 

200 

1 

16 

8 

1^ 

350 

1 

20 

10 

1^ 

550 

1 

24 

12 

1% 

75'0 

3 

24 

16 

1% 

1,000 

3 

30 

20 

11/2 

1,500 

3 

Shoe  Relaster. — The  Fern  Company  of  Baltimore 
has  placed  an  80  watt  relasting  iron  on  the  market  for 
the  use  of  the  retail  shoe  trade.  This  device  is  used 
for  smoothing  out  wrinkles,  creases,  and  irregularities 
in  shoes  and  otherwise  improving  their  appearance. 

Shoe  Machinery. — Electric  heat  has  been  applied 
to  various  machines  in  shoe  factories  with  marked  suc- 
cess. The  following  table  shows  various  applications 
of  electric  heat  to  standard  shoe  machinery. 


250 


ELECTRIC     HEATING 


Electrically  Heated  Shoe  Machinery. 

No.   of 


Application. 


Heating 
Unfts. 


Machine. 

Lining  Cementer 

Knurling    machine Knurl   holder 

Stitcher   Wax  pot 

Stitcher   Take-up    

Stitcher   Truck  on  wax  pot 

Stitcher   Shuttle    

Patent  leather  repairer....  Wax  receptacle... 

Stitcher    (old) Take-up    

Stitcher    (old) Shuttle    

Stitcher    (old) Wax    pot 2 

Stamper    Turret 2 

Embossing  machine Die    holder 2 

Embossing  machine Paste     1 

Upper      leather      stamping 

Machine    Die   Holder    .... 

Indenter  and  burnisher....  Knurl    holder     . 

Welter    Wax   pot    

Welter    Looper    

Welter    Tension     

Welter    Thread   tube .... 

Embosser    Die  Holder    .... 

Goodyear  stitch   burnisher.  Knurl  holder    .  . 

Bobbin   winder Wax   pot    

"Expedite"    Burnishing    iron 

"Expedite"    ,  Wax    pot 

Toe  softening  machine Boiler    

Solder  Pots. — For  heating  and  maintaining  correct 
temperature  for  soldering  operations,  electrically 
heated  pots  are  ideal.     They  are  much  cleaner,  safer 


Wattage 

of  Each 

Unit. 

200 

126 

75 
250 

63 
150 

63 
200 
126 

75 
182 
121 

38 

200 
126 

75 
182 

75 

38 
300 

75 
100 
425 
200 
750 


Westinghouse   S'older   Pot. 

and  simpler  to  operate  than  the  ordinary  charcoal  or 
gasoline  heated  pots.  The  standard  Simplex  pots  have 
the  following  sizes  and  capacities : 

5%"  xiy^"  deep  4  pounds  capacity  200  watts  three-heat. 
&%"  X  IVi"  deep  10  pounds  capacity  440  watts  three-heat. 
7%"xl^"    deep      20    pounds    capacity      825    watts      three-heat. 

The  standard  American  pots  have  the  following 
capacities : 

5  pounds  capacity  400  watts  three-heat. 

10  pounds  capacity  575  watts  three-heat. 

20  pounds  capacity  975  watts  three-heat. 

50  pounds  capacity  1500  watts  three-heat. 


GENERAL     APPLICATIONS  251 

Soldering  Irons. — Electric  soldering  irons  de- 
signed for  intermittent  use  are  manufactured  in  sizes 
varying  from  12  ounces  to  3  pounds,  and  consuming 
from  75  watts  to  350  watts,  respectively.     The  Simplex 


G.    E.    Soldering-    Iron. 

automatic  stand,  which  cuts  oft  one-half  the  current 
when  the  iron  is  placed  upon  it,  prevents  the  iron  be- 
coming overheated  when  not  in  use. 

Solution  Tanks. — The  General  Electric  Company 
has  devised  a  means  of  heating  solution  tanks  with  its 
cartridge  units.  One  3000  watt  installation  applied  to 
a  tank  of  7/16  in.  cast  iron  and  having  inside  dimen- 
sions of  18  in.  X  18  in.  x  14  in.,  is  said  to  bring  a  full 
tank  of  water  to  boil  in  about  thirty  minutes. 

Sterilizers. — The  application  of  electricity  to  the 
heating  of  sterilizers  offers  a  profitable  market  for 
energy  in  nearly  every  community.     All  modern  hos- 


Westinghouse    Instrument    Sterilizer. 

pitals,  Operating  rooms,  and  dental  offices  are  equipped 
with  sterilizing  devices,  and  the  cleanliness,  con- 
venience, and  healthfulness  afforded  by  electrically 
heated  apparatus  appeals  to  the  physician  or  dentist 
and  creates  a  favorable  impression  among  his  patients. 


552 


SLSCTRIC    hii:atl\(; 


American    Sterilizer    Installation.      (Left    to    right — In- 
strument, Water,  Utensil,  and  Dressing-  Sterilizers.) 

For  complete  sterilization,  dressings  are  kept  un- 
der a  steam  pressure  of  15  pounds  for  about  20  min- 
utes. AVater  is  maintained  at  250°  F.  in  closed  cham- 
bers for  approximately  the  same  period,  whereas  uten- 
sils and  instruments  are  submerged  in  boiling  water 
for  about  15  minutes. 

Several  makes  of  electrically  heated  sterilizers  are 
now  available.  Small  instrument  sterilizers  are  made 
by  the  Westinghouse,  Simplex,  Cutler-Hammer,  and 
other  heating  manufacturers.  The  American  Sterilizer 
Company  makes  a  complete  line  of  electrically  heated 
apparatus  of  this  character,  and  the  accompanying 
tables  gives  the  sizes,  capacities,  and  operating  fea- 
tures of  some  of  its  sterilizers  : 


Diam. 

Length 

Kw. 

Inches. 

Inches. 

Cap. 

9 

19 

3 

12 

20 

6 

14 

99 

6 

16 

24 

6 

16 

30 

6 

16 

36 

12 

Dressing    Sterilizers. 

Time  and  Energy  Required  for  One 
Sterilization.    Initial  Temp.  150°  F. 

Minutes  Minutes         Kw  -hr. 

High  Heat.  Low  Heat.  Consumed. 
14.5  20  .97 

13  20  1.8 

16.5  20  2.12 

18.5  2i0  2.32 

21  20  2.6 

15.5  20  4.1 


GENERAL     APPLICATIONS 


253 


AVater    Sterilizers. 


Gallons 
Capacity 

Kw. 

Capacity 

Time 
Steri] 

ana  lunerg-y  jrtequirea  lor  une 
lization.  Initial  Temp.  150°  F. 

per 

per 

Minutes 

Minutes          Kw  -hr. 

Reservoir. 

Reservoir     High  Heat 

Low  Heat.     Consumed. 

6 

3 

40 

20 

2.25 

8 

3 

44 

20 

2.45 

10 

6 

30 

20 

3.5 

15 

6 

40.5 

20 

4.52 

20 

12 

29.5 

20 

6.86. 

25 

12 

31.5 

20 

7.26 

35 

18 

32 

20 

11.1 

Utensil   Sterilisers. 

Time  an 

d  Energy  Required 

forO 

ne  Sterilization. 

Initial  Temp.  150°  F. 

4"   of  Water. 

Minutes 

Minutes       Kw  -hr. 

Dimens 

ions 

in  Inches. 

Kw. 

High 

Low              Con- 

Deptli. 

Width. 

Length. 

Cap. 

Heat 

Heat,          sumod. 

16 

15 

2(0 

6 

14 

15                 1.75 

20 

20 

24 

6 

25 

15                 2.87 

20 

24 

30 

12 

37 

15                 4,1 

24 

24 

30 

12 

.  . 

Instrument   Sterilizers. 

Time  and  Energy  Required 

forO 

ne  Sterilization. 

Initial  Temp.  150°  F. 

2"  of  Water. 

Minutes 

Minutes       Kw  -hr. 

Dimensions 

in  Ii 

nches. 

Kw. 

High 

Low              Con- 

Deptli. 

Width. 

Leng-th. 

Cap. 

Heat 

Heat,          sumed. 

6 

8 

16 

3 

7.5 

15                .55 

6 

10 

20 

3 

9.5 

15                 .66 

7 

12 

18 

6 

6.5 

15                 .98 

7 

12 

22 

6 

8 

15               1.19 

9 

12 

18 

6 

6 

15               1. 

9 

12 

22 

6 

8 

15               1.2 

It  should  be  observed  that  the  energy  consump- 
tions and  time  required  for  sterilization  is  based  in 
each  case  on  the  use  of  water  with  an  initial  temper- 
ature of  150°  F.  If  water  at  lower  temperature  is  used 
the  time  and  energy  consumption  will  naturally  be  in- 
creased. The  heating  units  employed  are  made  by 
the  concern  solely  for  its  own  use.  The  3  kw.  units 
have  three-heat  control  and  the  6  kw.  units  have 
seven  heat  control. 

Sweating-On  Machines. — An  application  typical  of 
the  advantage  of  electric  heat  over  the  open  gas  flame 
is  that  of  the  sweating-on  machine  for  mounting  cop- 
per electrotype  shells  upon  type  metal  blocks.  The 
block  is  placed  upon  the  heated  plate  until  the  solder 
foil  is  melted  and  the  block  with  the  shell  upon  it  is 
then  pressed  firmly  together  and  allowed  to  cool.     Cut- 


254  ELECTRIC     HEATING 

ler-Hammer  heating  elements  applied  to  machines  of 
this  character  are  said  to  produce  work  superior  in 
every  way  to  gas  heated  apparatus. 

Test  Tube  Heaters. — For  laboratory  use  the  Sim- 
plex test  tube  heater  is  convenient.  It  consists  of  an 
electrically  heated  grooved  casting  slightly  inclined 
from  the  perpendicular,  against  which  the  test  tubes 
may  be  rested.  The  standard  size  of  this  heater  is 
5  in.  X  7%  in.,  and  consumes  500  watts. 

Thread  Waxer  Heater. — A  wax  receptacle  of  a 
stitching  machine  may  be  heated  electrically  by  attach- 
ing a  low  wattage  unit  to  the  bottom.  A  number  of 
these  heaters  are  in  successful  use.  They  eliminate  all 
the  dangers  and  discomforts  of  gas  operation  and  are 
far  more  convenient  and  cleanly. 

Tire  Vulcanizers. — For  light  automobile  tire  re- 
pairs the  electric  vulcanizer  is  ideal.  Sand  blisters, 
cuts  and  stone  bruises  can  be  repaired  without  remov- 
ing the  tire,  and  as  the  work  can  be  done  promptly 
with  a  handy  device  of  this  kind,  it  will  save  much 
tire  expense.  The  heat  is  evenly  distributed  over  the 
surface  and  the  work  may  be  done  neatly  and  quickly. 


Shaler  Type  C  Inside 

Casing  Form.  S'haler   Type   E    Tube  Vulcanizer. 


The  C.  A.  Shaler  Co.  manufactures  a  complete 
line  of  electrically  heated  vulcanizing  forms,  which  it 
claims  to  be  equal  or  superior  to  its  steam  devices. 
Some  of  the  advantages  set  forth  are  simplicity,  porta- 
bility, quick  heating,  safety  and  non-confliction  with 
any  garage  regulations.  Each  device  may  be  pur- 
chased separately,  attached  to  any  work  bench,  and 
used  for  its  own  distinct  class  of  work.  The  capacities 
of  the  standard  devices  are  as  follows : 


GENERAL     APPLICATIONS  255 

Type  A — Outside   casing  form 70  watts 

Type  C — Inside  casing  form 80  watts 

Type  E — "Gang"    or   multi-tube   form    (4%"  x  24")  •  •  •  •  200  watts 

The  Westinghouse  automobile  tire  vulcanizer  con- 
sumes a  maximum  of  200  watts.  It  is  furnished  with 
a  15-point  rheostat,  a  thermometer,  and  a  flexible  cord. 


\i^ 


Westinghouse    Outside    Casing        Shaler  Type  A  Outside  Casing 
Vulcanizing  Outfit.  Form. 


Varnish  Tank  Heater. — A  well-lagged  varnish 
tank  5  ft.  high  and  3  ft.  in  diameter,  located  near  the 
roof  of  a  factory,  and  used  for  spraying  automobile 
bodies,  has  been  heated  by  three  3-heat,  900-watt 
cartridge  units  for  some  time.  The  units  are  placed  in 
a  10  in.  X  6  in.  X  3  in.  box  of  sand,  mounted  j^  in.  from 
the  bottom  of  the  tank,  and  the  leads  are  brought  out 
through  a  }i  in.  conduit. 

Velvet  Marking  Iron. — A  150  watt  General  Elec- 
tric iron  having  a  body  1  in.  square  by  6  in.  long  and 
a  bottom  surface  %  in.  wide  by  6  in.  long,  is  being  used 
by  the  J.  B.  Martin  Co.  of  Norwich,  Conn.,  for  marking 
letters  and  numbers  on  velvet  cloth.  A  gummed  cloth 
label  is  cemented  in  place  by  the  heat  and  pressure  ct 
the  iron. 

Water  Stills.  —  Electrically  heated  water  stills 
equipped  with  General  Electric  heating  units  have  been 
developed  by  the  Barnstead  Water  Still  Company  of 
Boston.  It  is  claimed  by  the  manufacturers  that  a 
2400  watt  still  will  provide  one  gallon  of  distilled  water 
per  hour. 


256 


ELECTRIC     HEATING 


E.   &  A.   Barnstead   Type   L  Water  Still. 

Wax  Burning-In  Irons. — Electrically  heated  burn- 
ing-in  irons  are  useful  in  furniture  factories  and  stores 
for  burning  in  wax.  They  are  usually  made  in  one 
pound  sizes  and  are  similar  to  soldering  irons  in  de- 
sign. 


G.  K.  Wax  Knife  Heater. 


Wax  Knife  Heater. — General  Electric  wax  knife 
heaters  are  superior  to  all  fuel  heated  devices  used  by 
cabinet  finishers.  The  standard  type  is  similar  to  a 
4-inch  disc  stove,  consumes  180  watts  and  is  designed 


GENERAL     APPLICATIONS  257 

with  an  insulating  cover,  under  which  the  knife  is 
placed. 

Weight  Reducing  Cabinet.  —  A  galvanized  iron 
cabinet  18  in.  in  diameter,  lined  v^ith  %.  in.  asbestos, 
has  been  equipped  by  the  General  Electric  Company 
with  two  of  its  tubular  type  500  watt  heating  units. 
Arrangement  is  made  for  heat  regulation  so  that  the 
attendant  may  vary  the  temperature  to  suit  the  pa- 
tient's needs. 

Yarn  Conditioning  Oven. — This  device  is  manu- 
factured  by  the  Tillotson  Humidifier  Company  of 
Providence,  R.  I.  It  is  used  for  measuring  the  mois- 
ture in  yarns  by  v^eighing  before  and  after  drying.  It 
is  well  insulated  and  thermostatically  controlled.  The 
oven  is  heated  with  two  General  Electric  600  watt 
units. 


CHAPTER  XVII 

RATES  FOR  HEATING  SERVICE. 

Establishing  of  Rates. — Electric  heating  service 
usually  differs  from  lighting  and  motor  service  in  its 
value  to  the  user  and  in  the  character  of  load  it  adds 
to  the  central  station  lines.  If  the  load  created  by  any 
class  of  service  is  sufficiently  attractive  to  warrant 
the  central  station  in  making  rates  for  it  that  are  equal 
to  or  less  than  its  value  to  the  user,  it  is  apparent  that 
an  ideal  condition  exists.  If  the  rate  is  of  necessity 
higher  than  the  customer  is  justified  in  paying  for  the 
service  rendered,  business  of  such  character  is  not  de- 
veloped, and  the  buyer  is  forced  to  obtain  the  same  or 
equivalent  service  elsewhere  at  a  less  cost.  On  the 
other  hand,  if  the  rate  must  be  made  so  low  to  obtain 
the  customer's  business,  that  the  additional  expense 
involved  is  greater  than  the  additional  income  secured, 
the  central  station  would  not  be  justified  in  making 
such  a  rate. 

Heating  Loads. — The  character  of  heating  loads 
varies  widely  on  account  of  the  diversity  of  application. 
From  an  operating  standpoint,  they  are  usually  more 
attractive  than  other  classes  of  load.  With  few  excep- 
tions they  are  non-inductive.  As  they  generally  oper- 
ate over  long  hour  periods,  they  tend  to  improve  the 
central  station  load  factors.  Fluctuations  of  the  cur- 
rent demand  are  less  marked,  and  as  many  electrically 
heated  appliances  naturally  take,  or  can  be  made  to 
take,  energy  only  during  off-peak  hours,  the  advan- 
tages are  obvious.  The  opportunity  for  building  up 
cooking  and  heating  loads  along  existing  residential 
and  rural  lines,  which  have  heretofore  required  enor- 
mous investment  in  proportion  to  gross  income,  is 
apparent.  , 

Rate  Maker's  Difficulties. — Many  central  station 
managers,  realizing  the  profitable  nature  of  the  electric 


RATES     FOR     HEATING     SERVICE  259 

heating  business  and  the  demand  for  such  rates  as 
will  foster  its  development,  have  been  anxious  to  make 
tariff  revisions,  but  have  been  undecided  as  to  the 
proper  course  to  pursue  by  the  apparent  adverse  atti- 
tude of  press,  public  and  the  various  regulating  bodies. 

x^s  a  whole,  the  public  is  notoriously  ill-informed 
on  central  station  rate  making  principles,  and  is  prone 
to  criticise  the  motives  actuating  those  who  make  rates 
for  certain  classes  of  service  lower  than  established 
rates  for  other  classes.  Furthermore,  the  attitude  of 
the  public  has  often  been  reflected  in  the  actions  and 
decisions  of  public  service  commissions.  The  fear  of 
criticism,  and  the  dread  of  establishing  harmful  prece- 
dents that  might  be  used  against  them,  deter  many 
responsible  concerns  from  making  rates  designed  to 
attract  new  and  profitable  business,  in  spite  of  their 
positive  convictions  that  such  action  would  be  produc- 
tive of  good  for  those  directly  concerned,  as  well  as 
for  the  public  at  large. 

It  may  be  observed  that  the  fear  of  popular  criti- 
cism and  the  dread  of  having  all  service  rates  reduced 
by  commission  rulings,  in  proportion  as  individual 
rates  are  lowered,  are  for  the  most  part  unfounded. 
Any  downward  revision  that  may  tend  to  improve 
living  conditions,  develop  new  industries,  or  result  in 
greater  good  for  a  greater  number,  must  eventually 
meet  with  universal  favor.  On  the  other  hand,  harsh 
criticism  must  sooner  or  later  come  upon  those  who 
do  not  offer  their  customers  the  benefit  of  such  rates 
as  they  can  well  afford  and  as  will  make  for  their 
mutual  welfare. 

N.  E.  L.  A.  Rate  Principles. — The  six  principles 
set  forth  in  the  1915  report  of  the  Rate  Research  Com- 
mittee of  the  National  Electric  Light  Association  are 
really  the  basis  of  intelligent  rate  making  in  the  elec- 
tric industry,  as  well  as  in  the  railroad  and  other  in- 
dustries. 

**(1)  The  total  net  income  of  the  company  must 
be  enough  and  no  more  than  enough  to  give  a  fair 
return  on  the  investment  and  attract  capital  freely  to 
the  enterprise.     The  gross  earnings  from  the  sale  of 


260  ELECTRIC     HEATING 

the  product  must  therefore  be  sufficient  to  cover  all 
necessary  expenses  of  operation,  including  taxes,  bad 
debts,  etc.,  a  reserve  for  renewals  and  contingencies, 
interest  at  current  rates  and  a  reasonable  profit  in  ad- 
dition. 

"(2)  When  conditions  are  the  same,  rates  to  dif- 
ferent customers  or  classes  should  be  the  same,  but 
need  not  necessarily  be  the  same  when  conditions  are 
diflferent. 

''(3)  No  rate  should  be  below  the  bare  cost,  i.  e., 
below  the  expense  involved  by  adding  that  customer 
or  class,  including  a  fair  return  on  any  investment 
added  or  used  exclusively  for  that  customer  or  class. 

"(4)  Rates  should  be  such  that  as  many  customers 
as  possible  may  be  served  at  as  low  rates  as  possible, 
and  yet  the  business  as  a  whole  furnish  a  fair  return 
on  all  the  investment. 

''(5)  No  rate  can  be  above  the  value  of  service, 
otherwise  the  customer  will  not  take  it. 

"(6)  While  cutomers  whose  circumstances  *are 
alike  should  pay  the  same  rates,  it  is  not  necessary 
that  customers  whose  circumstances  are  unlike  in  re- 
spect to  the  amount  their  class  can  afiford  to  pay, 
should  be  asked  to  pay  the  same  percentage  on  the 
investment  they  use  jointly,  especially  when  they 
would  not  take  the  service  if  asked  to  pay  such  rates, 
but,  on  the  other  hand,  would  take  the  service  and 
pay  something  toward  the  fair  return  on  the  whole 
investment  if  offered  rates  they  could  afford  to  pay. 

Application  of  Principles  to   Heating  Rates. — It 

is  apparent  that  in  applying  the  Rate  Committee's  prin- 
ciples to  the  establishment  of  rates  designed  to  develop 
certain  heating  loads,  the  central  station  is  justified 
in  making  rates  based  upon  the  actual  cost  of  supply- 
ing the  service,  plus  a  reasonable  return  upon  the  ad- 
ditional portion  of  the  investment  required  to  supply  it. 
It  is  not  essential  that  the  income  derived  from  the 
application  of  a  rate  shall  be  adequate  to  earn  a  re- 
turn upon  the  total  plant  investment  involved  in  sup- 
plying it. 


RATES     FOR     HEATING     SERVICE  261 

Each  central  station  company  must  decide  for 
itself  what  rates  it  shall  adopt,  because  the  matter  is 
one  that  naturally  depends  almost  entirely  on  local 
conditions.  It  is  obvious  that  the  present  tendency  is 
toward  wholesale  rather  than  retail  energy  supply  and 
rates  must  be  based  accordingly.  The  fact  should  be 
kept  in  mind  in  all  considerations  of  rate  matters  that 
a  mere  statement  of  rate  per  kilowatt  hour  does  not 
mean  very  much.  The  individuals  who  have  their 
money  invested  are  much  more  interested  in  annual 
returns  than  in  hourly  revenues. 


APPENDIX. 

Containing   References   and   Tables. 

Eleetrif  Heating  Mauufactiireri>(. 


Advance  Machinery  Co Toledo,  Ohio 

Glue  cookers  and  pots. 
American    Electric   Heater   Co Detroit,  Mich, 

Domestic  cooking  and  heating  devices. 

Industrial  heating  apparatus. 
American   Ironing  Machine  Co..  166  No.   Michigan   Ave.,   Chicago 

Simplex  ironing  machines. 
American   Laundry  Mach.   Co Cincinnati.   Ohio 

Mangles. 
Armstrong  Cork   &  Insulation   Co Cincinnati,   Ohio 

Heat    insulating   materials 
Barnstead   Water   Still   Co Boston,  Mass. 

Water  stills. 
C.  A.  Shaler  Co Waupun,  Wis. 

Vulcanizers. 
Chicago  Dryer  Co 624  So.  Wabash  Ave.,  Chicago 

Clothes  dryers. 
C.  H.  Sharp  Mfg.  Co 1312  E.  12th  St.,  Los  Angeles 

Electric   ranges. 
C.  L.  McBride  Mfg.  Co Toledo,  Ohio 

Glove  stretchers  and  laying-off  boards. 
Coin    Machine    Mfg.    Co Portland,   Ore. 

Induction  water  heaters. 

Induction   linotype  pots, 
Cutler-Hammer   Mfg.   Co 144th   St.   and  Southern  Blvd.,  N.   Y. 

Industrial   heating   apparatus. 

Domestic   heating   devices. 
C.  W.  Leavitt  &  Co Cortlandt  Bldg.,  New  York,  N,  Y. 

Girod   steel   furnaces, 
Driver-Harris  Wire  Co Harrison,  N.  J. 

Resistance  wire. 
Efficiency  Products  Co Rialto  Bldg.,  San  Francisco 

Water   heaters. 
Eimer   &   Amend   Co 205   Third   Ave.,  New   York,   N.  Y. 

Industrial   and   laboratory  heating  devices. 
Electric   Sales  Corporation 418   Union  St.,   Seattle,  Wash. 

"Apfel"    Water   Heaters. 
Elec+ric  Sales  Service  Co 109  Stevenson  St.,  San  Francisco 

'Therm   Elect"   water   heaters. 

Bacteriological  incubators. 
Electric  Specialty  Co Salt  Lake  City,  Utah 

Chicken   incubators   and   brooders. 
Electro    Hatch    Incubator    Co Petaluma,  Cal. 

Chicken   incubators  and   brooders. 
Estate  Stove  Company Hamilton,  Ohio 

Domestic  ranges. 
General   Electric  Co Schenectady,  N.   Y. 

Domestic  heating  and   cooking  devices.  , 

Hotel  and  domestic  ranges. 

Industrial    heating   devices,  , 

Geuder,  Paschke  &  Frey  Co Milwaukee,  Wis, 

Butt  welders. 
Globe  Stove  &  Range  Co ^ Kokomo,  Ind. 

Domestic  ranges. 
Good   Housekeeping  Cooker   Co Berkeley,    Cal. 

Automatic   cookers   and   water   heaters. 


264  APPENDIX 

Hamilton  &  Hansel! 17  Battery  Place,  New   York 

Rennerfelt  furnaces. 
Hoskins    Manufacturing    Co Detroit,   Mich. 

Small  furnaces  and  heating  devices. 
Hospital  Supply  Co 55  Fifth  Ave.,  New  York 

Sterilizers.   . 
Hotpoint    Electric    Heating-    Co Ontario.   Cal. 

Domestic  heating  and  cooking  devices. 

Electric  ranges. 
Hughes  Electric  Heating  Co 211  W.  Schiller  St.,  Chicago 

Domestic  and  commercial  cooking  devices. 

Bake   ovens,   etc. 
H.  W.  Johns-Manville  Co New  York,  N.  Y. 

Heat  insulating  materials. 

James  L.  Gibney  &  Bro Philadelphia 

Vulcanizers. 
James  B.  Clow  &  Sons 342  Franklin  St.,  Chicago 

Bath   cabinets. 
Landers,  Frary  &  Clark New  Britain,   Conn. 

Domestic  heating  and  cooking  devices. 
Lee  Electric  Radiator  Co 335  Wells  St.,  Chicago,  111. 

Water  heaters  and  radiators. 
Lincoln  Electric  Co E.  38th  St.  and  Kelley  Ave.,  Cleveland 

Arc  Welders. 

Majestic  Electric  Development  Co 428  O'Farrell  St.,  S.   F. 

Radiant  air  heaters. 
Michigan  Stove  Co Detroit,  Mich. 

Domestic    ranges. 

National    Electric   Utilities   Co 103    Park   Ave.,   N.    Y. 

Hotel  and   domestic  ranges. 
National   Electric  Welder  Co Warren,   Ohio 

Spot,  butt  and  seam  welders. 

Pelton   &  Crane   Co 244  Harper  Ave.,   Detroit,   Mich. 

Furnaces  for  jewelers  and  opticians. 
Petaluma  Incubator  Co Petaluma,   Cal 

Chicken   incubators  and  brooders. 
Prometheus  Electric  Co 232   E.  Third  St.,  New  York 

Sterilizers,   radiators,    etc. 
Presto  Electric  Co 323  Geary  St.,  San  Francisco 

Dental   heating  devices. 

Rathbone,    Sard    &   Co Albany,   N.   Y. 

Domestic  ranges. 
Rutenber  Electric  Co Logansport.  Ind. 

Domestic   ranges. 

Scanlan-Morris  Co Madison,  Wis. 

Sterilizers. 
Siemund.  Wenzel  Electric  Welding  Co 30  Church  St.,  N.  Y. 

Welding  machines. 
Simplex  Electric  Heating  Co Cambridge,  Mass 

Domestic   heating   and   cooking   devices. 

Hotel   and    domestic   ranges. 

Industrial    heating   devices. 
Snyder  Electric  Furnace  Co Chicago,  111 

Steel  furnaces. 
Standard  Electric  Stove  Co 1718  No.  12th  St.,  Toledo.  O. 

Domestic  ranges. 

Thomson    Electric   Welder   Co Warren,    Ohio 

Welding  machines. 

Union    Fibre    Co Winona,    Minn. 

Heat   insulating   materials 
United  Sales  Company Hobart  Bldg.,   San   Francisco. 

Automatic  water   faucets. 
United  States  Steel  Corporation Hoboken,  N.  J. 

Heroult  steel  furnaces. 
Vulcan  Electric  Heating  Co 107  W.  13th  St.,  New  York,  N.  Y. 

Branding  irons. 
Wenborne-Karpen  Dryer  Co 900  Michigan  Ave.,  Chicago 

Varnish   dryers. 


APPENDIX 


265 


Westinghouse  Electric  &  Mfg.  Co East  Pittsburgh,  Pa. 

Domestic  heating  and  cooking  devices. 

Domestic  ranges. 

Industrial   heating   devices. 
Wilmot,    Castle    Co Rochester,    N.    Y. 

Sterilizers. 
Winfield  Electric  Welding  Machine  Co Warren,  Ohio 

Welding  machines. 
Wm.  B.  Berry  &  Co 79  North  St.,  Boston,  Mass. 

Corn  poppers  and  peanut  roasters. 


Conversion  Data. 


kw  -hr.  =  3412   B.t.u. 
watthour  ==  3.412   B.t.u. 
wattminute  =  .0568  B.t.u. 
wattsecond  =  .0009477    B.t.u. 
large    calorie  =i  3.968    B.t.u. 
kw  -hr.  =  859.975   large   cal- 
ories. 
1   watthour  =  .859975   large 

calorie. 
1   wattminute  =  .01433    large 

calorie. 
1   wattsecond  =  .000239   large 

calorie. 
1   gallon   (U.  S.)  water  contains 

231   cu.    in.   or   .1337   cu.   ft. 
1  cu.  in.  of  water  contains  .00433 

gal.  and  weighs  .0361  lb. 
1   cu.  ft.  of  water  contains  7.48 

gal.,  and  weighs  62.428  lb. 
1   pound  of  water  =  27.68  cu.  in. 
1  pound   of  water  ==z. 958   pint. 
1   kilogram  of  water  =  1000  cu. 

cm. 
1   kilogram   of   water  =  1.0567 
quarts. 


1  B.t.u  =  .000293    kw -hr. 

1   B.t.u.  =  .293027   watthour. 

1   B.t.u  =  17.58  wattminutes. 

1   B.t.u.=r  1054.9    wattseconds 

1   B.t.u.  =  .25199   large   calorie. 

1   large     calorie  =  .001163     kw. 
hr. 

1  large    calorie  i=  1.163    watt- 
hours. 

1   large    calorie  =  69.769    watt- 
minutes. 

1  large  calorie  ==  4186.17   watt- 
seconds. 

1   large    calorie  =  1000     small 
calories. 

1   gram  of  water  =  1    cubic  cen- 
timeter. 

1   pounu    of    water  :=:  453.592 
cu.  cm 

1  kilogram    of   water  =  61.023 
cu.   in, 

1   kilogram    of    water  :==  .035314 
cu.    ft. 


Resistance   of  Conductors  at  Various  Temperatures. 

Rt  =  Ro  (1  +  xt). 
Rt  ^  resistance  at  temperature  t. 

Rft=r  resistance   at   temperature   given   in   standard   tables. 
X  =:  temperature  co-efflcient.    (Table  I.) 
t  =  difference  between  R^,  and  Rt. 


Table    1 — Relative    Resistance    and   Temperature    Coefficient. 


Relative  Resistance     Temp.  Coef. 
Pure    Metals.  in  per  cent.        Fahrenheit    (x) 

Silver  annealed    92.5  .00222 

Copper   annealed    97.5  .(00242 

Copper    (Standard)    100.0  

Gold    99.9    per   cent 138  .00210 

Aluminum  99  per  cent 161  .00235 

Zinc    362  .00226 

Platinum   annealed 565  .00137 

iron     570  .00347 

Nickel     778  .00345 

Tin    828  .00245 

Lead     1,280  .00228 

Antimony    2,21(0  .00216 

Mercury    5,930  .00044 

Bismuth     8,220  .00197 

Nichrome   (alloy)    .00024 


266 


APPENDIX 


Table    II. — Relation    of 


Load    Factor    aud    KiloAvatt-Hoiir    Cou- 
suinptlon. 


Load 

Factor 

per  cent. 

100 

90 

80 

70 

60 


Kw-hr. 
per  Year 
per  kw, 
8760 
7884 
7008 
6132 
5256 


Kw-hr. 

per  Month 

per  kw. 

730 
657 
584 
511 

438 


Load 
Factor 
per  cent 
&0 
40 
30 
20 
10 


Kw-hr. 
per  Year 
per  kw. 
4380 
3504 
2628 
1752 
876 


Kw-hr. 

jier  Month 

per  kw. 

365 

292 

219 

146 

73 


Table  III. — Relative  Radiating  and  Reflectingr  Power  of  Different 
Substances    (Kent). 


Radiating  or 
Absorbing  Power. 

Lampblack   100 

Water     100 

Carbonate  of  lead 100 

Writing  paper   98 

Ivory,  jet,  marble 93  to  98 


Ordinary    glass 

Ice    

Gum  lac   

Silver-leaf  on  glass 

Cast   iron,   bright   polished, 

Mercury,   about 

Wrought  iron,  polished.  .  .  , 

Zinc,  polished 

Steel,  polished   

Platinum  polished    

Platinum,  in  sheet 

Tin    

Brass,  cast,  dead  polished  , 

Copper,  varnished 

Brass,   bright   polished.... 

Copper,    hammered    

Gold,     plated     , 

Gold  on  polished  steel.... 
Silver,  polished  bright 


90 
85 
72 
27 
25 
23 
23 
19 
17 
24 
17 
15 
11 
14 


Reflecting  Power. 

0 

0 

0 

2 
7  to  2 
10 
15 
28 
73 
75 
77 
77 
81 
83 
76 
83 
85 
89 
86 
93 
93 
95 
97 
97 


Table    IV. — Transmission    of    Heat    Through    Plates    and    Tubes 

from    Steam    or    Hot    Water    to    Air.    (Kent). 

(B.t.u.  per  hour  per  sq.   ft.   per   degree   Fahr.   difference.) 

Copper,  polishea 0327     Sheet-iron,     ordinary 5662 

Tin,    polished    0440     Glass      5948 

Zinc  and   brass,  polished.    .0491      Cast    iron,    new 6480 

Tinned   iron,   polished....    .0858      Common    steam-pipe,    in- 

Sheet  iron,  polished 0920         ferred    6400 

Sheet    lead     1329      Cast     and     sheet     iron,, 

Wood,  building  stone,  and  rusted     6868 

brick     7358 

Table    V. — Boillus    Points    at    Atmospheric    Pressure 

14.7   lb.   per   square   inch.     (Kent). 

Deg.  F.  Deg.  F. 

Ether,    sulphuric    100     Av.    sea   water 213.2 

Carbon  bisulphide    118     Saturated    brine    226 

Ammonia    140     Nitric  acid 248 

Chloroform     140      Oil    of   turpentine 315 

Bromine     145     Phosphorus    554 

Wood    spirit    150     Sulphur 570 

Alcohol     173      Sulphuris  acid    590 

Benzine     176      Linseed    oil    597 

Water     212     Mercury    676 

The  boiling  points  of  liquids  increase  as  the  pressure  in- 
creases. The  boiling  point  of  water  at  any  given  pressure  is 
the  same  as  the  temperature  of  saturated  steam  of  the  same 
pressure. 


APPENDIX 


267 


Tabh 


Substance. 

Bismuth    

Cast  iron,  gray 

Cast  iron,  white 

Lead     

Tin     25.65 

Zinc    50.63 

Ice     144. 


VI. — Latent 

Latent  Heat 
of  Fusion 
in  B.t.u. 
.  .  .       22.75 
...      41.4 
.  .  .      59.4 
9.66 


Heat   of  FuMiou. 

Latent  Heal 

of  Fusion 

Substance.  in  B.t.u. 

Silver    37.93 

Beeswax     76.14 

Paraffine     63.27 

Spermaceti     66.56 

Phosphorus    9.06 

Sulphur     16.86 


Table   VII. — Meltlng-PointH   of  Various    Substances, 

T>eg.  F. 


Sulpliurous    acid 
Carbonic    acid     . 

Mercury  

Bromine     

Turpentine     


—  148 

—  108 

—  39 

•  + 
.        14 


9.5 


Hyponitric   acid    16 

Ice     32 

Nitro-g-lycerine     45 

Tallow    92 

Phosphorus     112 

Acetic   acid    113 

Stearine    109  to  120 

Spermaceti     .  .  ." 120 

Marg-aric  acid    131  to  140 

Potassium    136  to  144 

Wax     142  to  154 

Stearic  acid    158 

Sodium    194  to  208 

Alloy.    3    lead,    2    tin    and 

1  bismuth   199 

Iodine 225 

Sulphur    239 


(Kent). 
Deg.  F. 
Alloy,   1   tin,   1   lead ...  370  to  466 

Tin    442  to  446 

Cadmium    442 

Bismuth     504  to  507 

Lead    608  to  618 

Zinc    680  to  779 

Antimony    810  to  1150 

Aluminum     1157 

Magnesium    1200 

Calcium Full    red    heat 

Bronze     1692 

Silver    1733  to  1873 

Potassium  sulphate    1859 

Gold    1913  to  2282 

Copper    1929  to  1996 

Cast    iron,    white.  ..  1922  to  2075 

Cast   iron,   gray 2012  to  2228 

Steel    2372  to  2532 

Steel   hard,   2570;   mild 2687 

"Wrought   iron    2732  to  2912 

Palladium    2732 

Platinum     3227 


Alloy.  IVz   tin,  1  lead 334 

Cobalt,  nickel,  and  manganese,  fusible  in  highest  heat  of  a 
forge.  Tungsten  and  chromium,  not  fusible  in  forge,  but  soften 
and  agglomerate.  Platinum  and  iridium,  fusible  only  before 
the    oxyliydrogen    blowpipe. 

Table    VIII. — Specific    Gravity    of    Substances. 

Wt.    of   substance. 


S-p.Gr.  =-. 

Wt. 

Substance. 
Metals: 

Aluminum    .  .  . 

of  equal  bulk 

of  pure  water. 

Average 
Sp.  Gr. 

2  67 

Pounds  per 
cu.  ft. 

166  5 

Antimony    .  .  .  . 
Bismuth     

6.76 

... 9  82 

421.6 
612  4 

Brass:    Copper 

80 

-f  Zinc) 

20 

30      . 

40 

50      . 
r,   95   to 

5   to 

8  &0 

536  3 

70 

8  40 

523  8 

60 

8  36 

521  3 

50 

8.20 

511.4 

Bronze:    Coppe 

Tin, 
Cadimum    

80 

20 

8.53 

8.53 
8  65 

552.0 
552.0 
539 

Gold,  pure    .  .  .  . 

19  258 

1200  9 

Copper    

Iron,   Cast    .  .  .  . 
Iron,  Wrought 

8.853 

7.218 

7  70 

552. 
450. 
480 

Lead     

11.38 

709.7 

Manganese    .  .  . 

8. 

499. 

Magnesium    .  .  . 

1  75 

109 

Mercury    32° 

13  62 

849  3 

Mercury    60°    .  . 

13.58 

846.8 

268  APPENDIX 

Average  Pounds  per 

Substance.                                                                  Sp.  Gr.  cu.  ft. 

Mercury,    212°     13.38  834.4 

Nickel     8.8  548.7 

Platinum    21.5  1347.0 

Silver    10.505  655.1 

Steel    7.854  489.6 

Tin     7.35  458.3 

Zinc    7.00  436.5 

Wood: 

Ebony    1.23  76 

Oak,    Live    1.11  69 

Cedar    62  39 

Pine,    White    45  28 

Pine,   Yellow    61  38 

Cork     24  15 

Stoues,   Brick,  Cement,   etc.: 

Asphaltum    1.39  87 

Brick,  Soft 1.6  100 

Brick,  Common 1.79  112 

Brick,   Hard 2.0  125 

Brick,  Pressed   2.16  135 

Brick,   Fire    2.32  145 

Brickwork    in    mortar    1.6  100 

Brickwork  in  cement    1.79  112 

Cement,   Rosendale,    loose 96  60 

Cement,  Portland,  loose   1.25  78 

Clay     2.16  135 

Concrete     2.08  130 

Earth,   loose    1.22  76 

Earth,    rammed    1.60  100 

Emery     4.  250 

Glass     2.63  164 

Glass,  flint 3.02  188 

Gneiss     2.64  165 

Granite     2.64  165 

Gravel   1.76  110 

Gypsum    2.24  140 

Hornblende     3.36  210 

Lime,    quick,    in    bulk 84  53 

Limestone    2.96  185 

Magnesia,  Carbonate 2.4  150 

Marble     2.72  170 

Masonry,  dry  rubble    2.40  150 

Masonry,    dressed    2.56  160 

Mortar 1.52  95 

Pitch    1.15  72 

Plaster    of    Paris 1.23  77 

Quartz     2.64  165 

Sand     1.60  100 

Sandstone     2.32  145 

Slate    2.80  175 

Stone,   various    2.78  168 

Trap     3.06  185 

Tile    1.84  115 

Soapstone     2.73  170 

Liquids    (at    60°    F.): 

Acid,   Muriatic    1.200 

Acid,  Nitric    1.217 

Acid,  Sulphuric    1.849 

Alcohol,    pure     794 

Alcohol,    95</^    816 

Alcohol,    50%    934 

Ammonia,   27.9% 891 

Bromine    2.97 

Carbon    disulphide    1.26 

Ether,  Sulphuric 72 

Oil,    Linseed     94 

Oil,   Palm    97 

Oil,   Olive    92 

Oil.    Petroleum     83 


APPENDIX 


269 


Substance. 
Oil,  Rape 


Average 

Sp.  Gr. 

.92 

.87 

.92 

1. 


Pounds  per 
cu.  ft. 


Oil,  Turpentine    

Oil,  Whale    

Vinegar     ....  .'..'....' 1.08 

Water    1. 

Water.   Sea    1.028 


Gases    (at   62°   F.    Water  =  1): 

Oxygen    

Mltrogen  . 

Hydrogen     

Argon    

Carbon    

Phosphorus    

Sulphur     

Silicon     

Air 

Water-vapor 

Ammonia     

Carbon   monoxide    (Carbonic   oxide) 
Carbon  dioxide   (Carbonic  acid)  .... 

defiant  gas   

Marsh  gas 

Sulphurous    acid    

Sulphuretted    hydrogen    

Bisulphuret  of  carbon 

Ozone     


0.001350 

0.001185 

0.0000846 

0.001607 

0.001013 

0.0026221 

0.002705 

0.001184 

0.001221 

0.0007613 

0.0(0118 

0.002369 

0.00187 

0.001181 

0.000675 

0.002493 

0.002877 

0.00643 

0.00203 


0.0814 
0.0738 
0.00527 

'0.63131 

0.16337 

0.16861 

0.07378 

'0.0761 

0.04745 

0.0448 

0.07364 

0.11631 

0.0736 

0.04209 

0.15536 

0.17918 

0.40052 

0.12648 


*By  this  table  there  would  be  12.75  cubic  feet  of  air  at  32°  F. 
per  pound. 

The  specific  heats  of  substances,  as  given  by  different 
authorities,  show  considerable  lack  of  agreement,  especially  in 
the   case    of    gases. 

The  following  tables  give  the  mean  specific  heats  of  the 
substances  named  according  to  Regnault.  These  specific  heats 
are  average  values,  taken  at  temperatures  which  usually  come 
under  observation  in  technical  application.  The  actual  specific 
heats  of  all  substances,  in  the  solid  or  liquid  state,  increase 
slowly  as  the  body  expands  or  as  the  temperature  rises.  The 
specific  heat  of  a  body  when  liquid  is  greater  than  when  solid. 
For  many  bodies  this  has  been  verified  by  experiment. 


Table    IX. — Specific    Heats    of    Various    Substances.      (Kent.) 


Solids. 


Antimony    0.0508 

Copper     0.0951 

Gold     0.0324 

Wrought   Iron    0.1138 

Glass     0.1937 

Cast  Iron    0.1298 

Lead    0.0314 

Platinum    0.0324 

Silver    0.0570 

Tin      0.0562 


Steel    (soft)     0.1165 

Steel    (hard)     0.1175 

Zinc    0.0956 

Brass     0.0939 

Ice     (0.5040 

Sulphur     0.2026 

Charcoal 0.2410 

Alumina     0.1970 

Phosphorus     0.1887 


Liquids. 


Water    1.0000 

Lead   (melted)    0.0402 

Sulphur    (melted)     0.2340 

Bismuth    (melted)     ....  0.0308 

Tin,   (melted)    '0.0637 

Sulphuric    acid     0.3350 


Mercury     0.333 

Alcohol   (absolute)    0.7000 

Fusel    oil    0.5640 

Benzine     0.450a 

Ether     0.5034 


270 


APPENDIX 


Gases. 

Constant 
Pressure. 

Air     0.23751 

Oxygen     0.21751 

Hydrog-en     3,4090'0 

Nitrogen     0.24380 

Superheated    steam    0.4805 

Carbonic  acid 0.217 

Oleflant   Gas    (CH,) 0.404 

Carbonic     oxide     0.2479 

Ammonia    0.508 

Ether     0.4797 

Alcohol    0.4534 

Acetic    acid     0.4125 

Chloroform    0.1567 


Constant 
Volume. 

0.16847 

0.15507 

2.41226 

0.17273 

0.346 

0.1535 

0.173 

0.1758 

0.299 

0.3411 

0.3200 


'ruble  X. — Lineal  E^xpansion  of  Solids  at  Ordinary  Temperatures. 

(Clark.)  For  1° 

Fahrenheit. 
Length  =  1 

Aluminum    (cast) 00001234 

Antimony   (cryst.)    00000627 

Brass,    cast    00i000957 

Brass,  plate    00001052 

Brick    00000306 

Bronze    (Copper,    17;    Tin,    2%;   Zinc,    1) 00000986 

Bismuth     00i000975 

Cement,    Portland    (mixed),    pure 00000594 

Concrete;   cement,   mortar,   and  pebbles 00000795 

Copper    00000887 

Ebonite  * 000/04278 

Glass,    English    flint    00000451 

Glass,    thermometer    00000499 

Glass,    hard    '. 00000397 

Granite,  gray,  dry 00(000438 

Granite,  red,  dry    00000498 

Gold,    pure    00000786 

Iridium,    pure     00000356 

Iron,    wrought     00000648 

Iron,   cast    00000556 

Lead    00001571 

Magnesium    

Marbles,    various,    from    00000308  to  .00000786 

Masonry,     brick,    from 00000256  to  .00000494 

Mercury    (cubic    expansion)     00009984 

Nickel  ^ 00000695 

Pewter    00001129 

Plaster,    white    00000922 

Platinum    0*0000479 

Platinum,   85  per  cent 00000453 

Iridium,  15  per  cent 00000453 

Porcelain .00000200 

Quartz,  parallel  to  major  axis,  t  0°   to  40°   C i00000434 

Quartz,  perpendicular  to  major  axis,  t  0°   to  40°   C.  .      .00000788 

Silver,   pure    00001079 

Slate    00000577 

Steel,  cast    0i0000636 

Steel,    tempered    00000689 

Stone    (sandstone)    dry 00000652 

Stone    (sandstone)    Rauville 00000417 

Tin    00001163 

Wedgewood   ware    (00000489 

Wood,    pine 00000276 

Zinc 00001407 

Zinc  8,  tin  1 00001496 

Cubical  expansion  or  expansion  of  volume  =:  linear  expansion  x  3 


APPENDIX 


271 


Table   XI. — Character   of   Bmltted   Liiglit   and    Corresponding: 
Approximate   Temperature.    (Babcock   and    Wilcox.) 

Character    of    Emitted    Light.  Temp.  F.° 

Dark   red,   blood   red,   low   red 1050 

Dark    cherry    red 1175 

Cherry,    full    red    1375 

Ligrht  cherry,   bright  cherry  and  light  red 155i0 

Orange    1650 

Light  Orange    1725 

Yellow    1825 

Light   Yellow    1975 

White    2200 

♦(Character    of    emitted    light    and    corresponding    tempera- 
tures approximately  the  same  for  all  materials). 

Table  XII. — Weight  of  W'ater  at  Temperature  Used  in   Standard 
Calculations.    (Babcock   &  Wilcox — "Steam"). 

Weight  per  cu.  ft. 
Temperature    Degrees    Fahrenheit.  in  Pounds. 

At   32°   freezing  point  at  sea  level 62.418 

At  39.2°  or  point  of  maximum  density 62.427 

At   62°    or    standard    temperature 62.355 

At   212°    or   boiling   point    at   sea   level 59.846 

Table   XIII. — Variations   in  Properties   of   Saturated   Steam   ^vith 

Pressure. 


(From   Marks   &   Davis 

Tables.) 

Pressure 

Pounds 

Absolute. 

Temperature 

Degrees 
Fahrenheit, 

Heat  of 
Liquid 
B.t.u, 

Latent 
Heat 
B.t.u, 

Total  Heat 
B.t.u. 

14.7 

20.00 

100.00 

300.00 

212.0 
228.0 
327.8 
417.5 

180.0 
196.1 
298.3 
392.7 

970.4 
960.0 
888.0 
811.3 

1150.4 
1156.2 
1186.3 
1204.1 

Table    XIV. — Saturated    Steam.     (From 

Tables.) 

Gauge   Pressure. 

10 

20 

30 

40 

50 

60 

70 

80 

90 
100 
110 
120 


Marks    &    Davis'    Steam 


B.t.u. 

Total  B.t.u.  in  Steam 

161.1 

1143.1 

196.1 

1156.2 

218.8 

1163.9 

236.0 

1169.4 

250.1 

1173.6 

262.1 

1177.0 

272.6 

1179.8 

282.0 

1182.3 

290.5 

1184.4 

298.3 

1186.3 

305.5 

1188.0 

312.3 

1189.6 

Table   XV. — Calorifte  Values   of  Dry   Wood.    (Gottlier.) 
Kind  of  Wood.  B.t.u.  per  lb. 

Oak    8316 

Ash     8480 

Elm    8510 

Beech    8591 

Birch     8586 

Fir    9063 

Pine    9153 

Poplar    7834* 

Willow     7926* 

*B.t.u.  calculated. 


272 


APPENDIX 


Table  XVI — Calorific  Value  of  General  Grades  of  Coal  on   BaNls 


of  Combustible.   ( Aiiproximate.) 

Per  Cent  of  Combustible. 
Fixed  Carbon.        Volatile  Matter. 


Antracite    97.0   to   92.5 


Semi-anthracite  .... 
Semi-bituminous  .  .  . 
Bituminou.s — Eastern 
Bituminous — \yestern 
Lignite   


92.5  to  87.5 
87.5  to  75.0 
75.0  to  60.0 
65.0  to  50.0 
Under  50 


3.0   to     7.5 

7.5   to   12.5 

12.5   to   25.0 

25.0   to   40.0 

35.0   to   50.0 

Over   50 


B.t.u. 
Per  Pound  of 
Combustible. 

14600  to  14800 
14700  to  155i00 
15500  to  16000 
14800  to  15300 
13500  to  14800 
11000   to   13500 


Table  XVII. — Calorific  Value  of  Various   Oils. 


Kind    of    Oil. 
California,  Coalinga    ...... 

California,  Bakersfield    .  .  • 
California,   Bakersfield    .... 

California,   Kern    River.  .  .  . 

California,  Los  Angeles... 
California,  Los  Angeles... 
California,  Los  Angeles.  .  . 
California,   Monte     Christo. 

California,   Whittier    

California,  Whittier    ...... 

Texas,    Beaumont    

Texas,  Beaumont   

Texas,  Sabine .  . 

Ohio    

Pennsylvania    

West   Virginia 

Mexico 


B, 


t.u.  per.  lb. 
17117 
176.00 
18257 
18845 
18328 
18855 
18280 
18878 
18507 
18240 
20152 
19349 
18662 
19580 
19210 
21240 
18840 


Authority. 
Babcock  & 
Wade 
Wade 
Babcock  & 
Babcock  & 
Babcock  & 
Babcock  & 
Babcock  & 
Wade 
Wade 
Sparkes 
Babcock  & 
Babcock  & 


Wilcox 


Wilcox 
Wilcox 
Wilcox 
Wilcox 
Wilcox 


Wilcox 
Wilcox 


Booth  s 

Babcock  &  Wilcox 


Table   XVIII. — Calorific   Values   of   ]\atural    Gas. 

B.t.u  per  cu.  ft. 

Locality    of    Well.  Calculated.* 

Anderson,    Ind 1017 

Marion,    Ind 1009 

Muncie,   Ind 1004 

Clean,    N.    Y 1018 

Findlay,    O 1011 

St.  Ive,   Pa 1117 

Cherry  Tree,  Pa 842 

Grapevine,    Pa 925 

Harvey  Well,  Butler  Co.* 998 

Pittsburgh,    Pa 748 

Pittsburgh,    Pa 917 

Pittsburgh,    Pa 899 

*B.t.u.   Approximate. 


Table  XIX — Approximate  Calorific  Values  of  Various  Gases  (Kent) 

B.t.u. 
Kind  of  Gas.  per  Cu.  Ft. 

Natural  gas   1,000 

Coal    gas     675 

Carburetted  water  gas 646 

Gasoline  gas    690 

Water   gas  from   coke 313 

Water  gas  from  bituminous  coal 377 

Producer  gas 150 

Naptha-gas    (21/2    gal.   per  1000   cu.   ft) 306 


APPENDIX  273 

Table    XX. — Refractory    Materials    (Stansfield.) 

Melting 
Temperature 
Material.  Deg.  F. 

Fire-clay   brick.     Kaolin   with   additional    silica.  ..  .2900  to  3150 

Silica-brick.      Silica   with    binding   material 3100 

Silica     (pure)     3180 

Bauxite    (impure    alumina)     3300 

Alumina  (pure)    3650 

Lime    (pure)     about     3700 

Chrome-brick     3700 

Chromite    3950 

Magnesia-brick    3900 

Magnesia    (pure)    about     4000 

Carborundum,   SiC    decomposes     4000 

Carbon    vaporizes   rapidly     6500 


INDEX 


Air  heating, 

advantages  and  use  of,  115,  116,  117. 

calculations  and  formulae,  124-129. 

cost  of,  117. 

heater,  installation  of  123,  124. 

systems,  117-124. 

transmission  losses,  126. 

with  convection  heaters,  120-121. 

with  indirect  heaters,  122,  123. 

with  oil  and  water  radiators,  121,  122. 

with  steam  and  hot  water  distribution,  123. 

with  radiant  heaters,  118-120.\ 
Apartment  houses,  electric  ranges  in,  35-38. 

wiring,  24. 
Arc,  cutting,  (see  welding). 

furnaces,  (see  furnaces), 

welding,  (see  welding). 
Automofbile,  hood  heater,  221. 

tire  vulcanizer,  254. 

Automatic  water  heaters,  104-105, 

Bacteriological  incubators,  221. 

Bake  ovens,  14,  83-92. 

advantages  of,  88, 
construction,  84. 
diversity  of  baking,  91. 
extent  of  use,  83. 
features  of,  85. 
floor  space,  90. 
for  roasting,  91, 
General  Electric,  86, 
Hughes.  86, 
regulation  of,  89. 
sanitary  features,  90, 
Simplex,  85. 

Baking,  of  breads  and  pastries,  40,  41,  88-92. 
temperatures,  41. 

Batch  warmer,  224. 

Bath  cabinets,  222,  257. 

Beer  vat   dryer,   223. 


276  INDEX 

Boilers,  steam,  214-220. 

advantages  of,  214. 

apparatus,  219,  220. 

application  of,  214. 

calculation  of  capacities,  214-220. 

cost  of  operation,  218. 

efficiencies  of,  214,  215. 

electric,  217. 

energy  required,  218. 

horsepower,  215. 
Boiling  points,  table  of,  265. 
Branding  irons,  134,  223,  239,  243,  244. 
British  thermal  unit,  3. 
Broilers,  meat,  75,  77. 
Brooding  of  chickens,  191-196. 

advantages  of,  193. 

apparatus,  192. 

costs    of,    195. 

methods  of,  191. 

Burning-in,  wax  irons,  256. 
Butt  welding,   (see  welding). 
Button  die  heaters,  223. 

Cabinets,  bacteriological,  221. 

bath,  222. 
Calorie   3. 

Calorific  values,  of  fuels,  271. 
Can  capping  machine  heater,  224. 
Candy  batch  warmer,  224. 
Carrying  capacity  of  wires,  19. 
Celluloid,  embossers  224. 
Chafing  dishes,  10. 
Chicken,  brooding,  (see  brooding). 

incubating,    (see  incubating). 

Chocolate,  side  pans,  226. 

warmers,  225. 
Clothes  dryers,  226. 
Coal,  calorific  values  of,  271. 
Coffee,  percolators,  11. 

roasters,  246. 

urns,   82. 

Commercial  cooking,  68-92. 

advantages  of,  68. 

apparatus.  69,  71. 

opportunities,  68. 

planning  equipment,  68. 

Conduction  of  heat,  5. 

Convection,  heaters,  120-121. 
of  heat,  5. 


INDEX  277 

Conversion  data,  264. 

Cooking,  electric,  advantages,  25,  35-38,  68. 

in  apartment  houses,  35-38. 

in  hotels  and  restaurants,  68-92. 

in  schools,  34,  35. 

of  breads  and  pastries,  40-41. 

of  meats,  39. 

of  vegetables,  40. 

purposes  of,  38. 

reason  for,  38. 
Corn  popping  machines,  227. 
Corset  irons,  227. 
Creasing  tools,  239. 
Curling  irons,  16. 

Die   heaters,   223,   245. 

Dining  room  sets,  12. 

Disc  stoves,  9. 

Domestic   science  departments,   34,  35. 

Dryers,  clothes,  226. 

envelope,  228. 

fan,  228. 

film,  229. 

matrix,  241. 
Drying  ovens,  182,  227. 

photographic,  247. 

Egg  boilers,  17. 

Electric,  (see  cross  references). 

Electrodes,  (see  cross  index).  , 

furnace,  (see  furnaces). 

welding,  (see  welding). 
Elements,  enclosed  types,  43. 

radiant   types,   44. 

reflector  types,  45. 

types  of,  43-46. 
Embossers,  celluloid,  224,  227. 
Enameling  furnaces,  (see  furnaces). 
Engraver's  stoves,  228. 
Envelope  gum  dryers,  228. 
Expansion  of  solids,  269. 

Factors  of  evaporation  table,  216. 
Ferro-alloys,  156. 
Film  dryers,  229. 
Flanging  bags,  233. 
Flask,  heaters,  230. 
Food,  preparation  of,  38-41. 
warmers,  13. 


278  INDEX 

Foot  warmers,  18. 
Frying,  griddles,  82. 

kettles,  79. 

pans,  17. 

Furnaces,  electric    145-184. 

advantages,  145,  151,  163,  174,  178. 
aluminum,  161. 
arc  types,  149,  150,  164. 
direct,  150,  167,  171. 
indirect,   150.   167,   169. 
series,  150,  167,  173. 
classification  of,  149-150,  174,  175. 
commercial  features,  156. 
cost  of  operation,  151. 
efficiency,  152, 
electrodes,   154,   155. 
electrolytic  production,  150,  160,  161 
energy  required,  152. 
ferro  alloys,  156-157. 
field   for,   145,   163,   174,   177. 
graphite,  150,  159. 
induction,  150,  164,  165. 
iron  ore  smelting,  157. 
losses,  153,  183. 
low  temperature,  174-184. 
carbon  resistance,  175. 
drying,  182. 
enameling.  177-184. 
metallic  resistance,  175. 
processes,  174. 

temperatures  required,  174,  177. 
nitrogen  fixation,  162. 
products,  miscellaneous,  162. 
power  loads,  147-149,  162,  168,  170. 
refractories,  154,  272. 
resistance  types,  149,  150,  174,  175. 
smelting,  157-159. 
steel,  163-173. 

advantages  of,  163. 
production  of,  163. 
smelting,  164. 
types  of,  149-184. 

Acheson  carborundum,  149. 

Colby,  166. 

Electro-metals,  171. 

Frick,  166. 

Gin,  164. 

Girod,  150.  171,  172. 

Heroult,  150,  173. 

Hoskins,  176. 

Keller,  171,  172,  173. 

Kjellin,  165. 

Rennerfelt,  169. 


INDEX  279 


Rochling-Rodenhauser,  166. 

Snyder,  172. 

Stassano,  150,  169. 
tube  150. 
walls  of,  153,  154,  183. 

Gas,  calorific  values  of,  271. 
Gilding  wheel  heater,  230. 
Glove,  laying-off  boards,  230. 

stretchers,  230. 
Glue,  cookers,  232. 

pots,  231. 
Gold  leaf  stamp  heaters,  232. 
Griddles,  frying,  82. 

hot  cake,  82. 
Grills,  domestic,  13. 
Grounding  of,  flexiWe  conduit,  23. 

flexible  steel  armored  conductor,  23. 

heating  appliances,  24. 

metal  moulding,  22. 

neutrals,  24. 

rigid  conduit,  22. 
Hand,  flats,  233. 

shells,  233. 
Hatters',  flanging  bags,  233. 

hand  flats,  233. 

hand  shells,  233. 

machine  irons,  234. 

velouring  stoves,  234. 
Heat,  absorbed  by  air,  125. 

advantage  of,  1,  115-117,  131. 

comparative  costs,  of,  6,  117,  131. 

conducted,  5. 

convected,  5. 

demand  for,  1. 

diversity  of  use,  221. 

fuel,  6. 

latent,  4,  153. 

measurement  of,  2,  3. 

mechanical  equivalent  of,  3. 

nature  of,  1. 

radiant,  5,  118-120. 

relation  to  electrical  units,  3. 

sensible,  4. 

specific,  2. 

transmission  of,  126. 
Heaters,  (see  cross  index). 
Heating,   (see  cross  index). 

device  manufacturers,  262-264. 

elements,  132-133,  235-237. 

industrial,   (see  cross  index). 


280  INDEX 

loads,  258. 

of  buildings,  (see  air  heating),  115   129. 

of  water,  93-114. 

tanks,  241. 
Hot,  air  blower,  235. 

cake  griddles,  82. 

closets,  14,  77. 

pads,  16. 

plates,  9,  237-238. 
Hotel,  cooking,  (see  commercial  cooking). 
Hood  heaters,  automobile,  221. 
Hovers,  (see  brooding). 

Immersion  heaters,  17,  101,  108. 

Inculbating,  advantages,  191. 

apparatus,  189. 

bacteriological,  221. 

chickens,  186. 

costs  of,  191. 

methods  of,  185. 

poultry,  185,  191. 
Industrial  heating,  (see  cross  index). 

advantages  of,  131. 

applications  of  134-144,  221. 

comparative  cost  of,  131. 

development  of,  130. 

elements,  132-133. 

field  for,  130,  221. 

specifications  for,  133,  134. 

units,  235-237. 

Installation,  of  heating  apparatus,  19. 
of  ranges,  19,  25. 
of  wiring,  19. 

Instantaneous  water  heating,  100. 

Iron  ore  smelting,  157. 

Irons,  branding,  223,  239,  243,  244. 
burning-in,  wax,  256. 
corset,  227. 
curling,  16. 

domestic,  8,  18.  ' 

hatters',  233-235. 
laundry,  238. 
soldering,  251. 
tailors,  238. 
velvet  marking,  255. 

Japanning  ovens,  (see  low  temperature  furnaces) 

Kettles,  pitch,  247. 
Knife  heater,  wax,  256. 


INDEX  281 


Laboratory,  flask  heaters,  230. 

furnaces,  (see  furnaces). 

hot  plates,  237-238. 

test  tube  heaters,  254. 
Lagging,  application  of,  113,  114. 

Economy,  111. 

Keystone,  111. 

materials,  111-114. 

of  tanks  and  pipes,  96-98. 
Latent  heat,  4, 

of  evaporation,  4,  153. 

of  fusion,  4,  266. 

of  sublimation,  153. 
Laundry,  irons,  238. 

clothes  dryers,  226. 

machines,  237. 
Laying-off  boards,  glove,  230. 
Leather  creasing  tools,  239. 
Liquid  heating  tanks,  241,  251. 
Linear  expansion  of  solids,  269. 
Linotype  pots,  239. 
Load  factors,  table  of,  265. 

Manufacturers,  list  of,  262-264. 
Matrix  dryers,  241. 
Meat,  branders,  243. 

broilers,  75-77. 

preparation  of,  39. 

shrinkage  of,  28,  68,  70,  92. 
Mechanical  equivalent  of  heat,  3. 
Melting,  points  of  substances,  266,  272. 

pots,  239,  248,  250. 

tanks,  243. 
Metal  melting,  pots,  239,  248,  250. 

tanks,  243. 

Milk  warmers,  15. 
Moistener,  paper  seal,  246. 
Monotype  pots,  239. 

Oil,  calorific  values  of,  271. 
tempering  baths,  244. 

Ovens,  commercial  baking,   83-92. 
General  Electric,  86. 
Hughes,  86. 
Simplex,  85. 

domestic  baking,  14. 

drying,  182. 

enameling,  177-184,  (see  furnaces). 

for  industrial  heating  (see  furnaces! 


282  INDEX 

heating  units,  182. 

revolving,  182. 

yarn  conditioning,  257. 


Pallette  die  heaters,  245. 
Paper  seal  moistener,  246. 
Peanut  roasters,  246. 
Percolators,  11. 
Perforator  for  drawings,  246. 
Photographic  drying  ovens,  247. 
Pipe  thawing  outfits,  247. 
Pitch  kettles,  247. 
Plate  warmers,  14,  77. 
Pleating  machine  heaters,  248. 
Plumbing,  air  pockets,  110. 

by-passing,  109. 

design  of  systems,  110. 

for  water  heating  systems,  107-111. 

heater  installation,  108. 

pipe  connections,  108. 

return  systems.  111. 
Poultry,  brooding,  (see  brooding). 

incubating,  (see  incubating). 
Pouring  pots,  248. 
Ptess,  blocks,  227. 

heads,  227. 

heaters,  em'bossing,  227. 
Printing  ink  heater,  248. 

Radiation,   of  heat,  5,   118-120. 
Radiating  power  of  substances,  265. 
Radiators   air,  18,  118-124. 
installation  of,  123. 
Ranges,  domestic,  42-66. 

Acorn,  60. 

Estate,   58. 

Garland,  64. 

General  Electric,  50. 

Globe,  57. 

Good  Housekeeping,  55. 

Hotpoint,  65. 

Hughes,  46. 

Olsten,  54. 

Rutenber,  60. 

Simplex,  48. 

Standard,  61. 

Westinghouse,  52. 
economical  operation,  30. 
hotel    72-75. 

General  Electric,  73. 


INDEX  283 


Simplex,   73. 
in  apartment  houses,  35-38. 
operation   by   servants,   32. 
Rates,  establishment  of,  258. 

for  heating  service,  258-261. 
principles  of,  259,  260. 

Rectifier  tube  boiler,  248. 
Reflecting  power  of  substances,  265. 
Refractories,  (see  furnaces). 

table  of  melting  temperatures,  272. 
Resistance,  (see  cross  index). 

furnaces,  (see  furnaces). 

of  conductors,  264.  * 

relative,    264. 

welding,   (see  welding). 
Restaurant  cooking,   (see  commercial  cooking), 
Return  system  of  piping.  111. 
Roasters,  coffee,  246. 

peanut,  246. 
Roasting  of  meats,  39,  91. 

Schools,  cooking  in,  34,  35. 
Sealing  wax  pots,  248. 
Shelf  heaters,  249. 
Shoe,  machinery,  249. 

relaster,  249. 
Shrinkage  of  meats,  28,  68,  70,  92. 
Side  pans,  chocolate,  226. 
Smelting,  of  copper,  zinc,  etc.,  159. 

of  iron  ore,  157, 
Specific,  gravity  of  substances,  266. 

heat,  definition,  etc.,  2,  3. 

heat,  of  substances,  268. 
Spot  welding,  209-210. 

Steam,  boilers,   (see  boilers), 
heat,  131. 
properties  of,  270. 
saturated,  270. 
talbles,  77. 

Steel  furnaces,  163-173. 
Stills,  water,  255. 
Stretchers,  glove,  230. 
Soldering,  irons,  251. 

pots,  250. 
Solution  tanks,  251,  255. 
Soup  tureens,  17. 
Sterilizers,  251-253. 
Stoves,   (see  ranges). 


^84  INDEX 

disc,  9. 

engravers,  228. 
printers,  248. 
velouring,  234. 

Sweating  blankets,  17. 
Sweating-on  machines,  253. 
Switches,  control,  24. 
entrance,  24. 


Table  cooking  outfits,  12. 
Tailors'  irons,  238. 
Tea  kettles,  12. 

samovars,  12. 
Temperature,  character  of  emitted  light,  270. 

coefficients,  table  of,  264. 

comparison  of  Fahrenheit  and   Centigrade,  2. 

measurement,  2. 
Tempering,  baths,  244. 

ovens,  175. 

Test  tube  heaters,  254. 

Thawing  outfits,  247. 

Thermal  storage,  water  heating,  99,   (see  water  heating), 

Thermometers,  Fahrenheit  and  Centigrade,  2. 

Thread  waxer  heater,  254. 

Tire  vulcanizers,  254. 

Toaster  stoves,  domestic,  9,  137 

hotel,  79. 
Thermal  capacity,  3. 
Transmission  of  heat,  table  of,  265. 

Underwriters'  code,  19,  20  25. 
Units    enclosed  types,  43. 

industrial,   235-237,   249. 

radiant  types    44. 

reflector  types,  45. 

types  of  43-46. 
Urns,  coffee,  82. 
Utensils,  kinds  to  use,  29. 

Varnish  tank  heater,  255. 
Vat  dryer,  223. 
Velouring  stoves,  234. 
Velvet  marking  iron,  255. 
Voltage,  correct,   21. 

drop  in,  20. 
Vulcanizer,  roofing  material,  248. 

tire,  254. 


INDEX  285 


Waffle  irons,  83. 

Warmers,  chocolate,  225. 

Warming  pads,  16. 

Water,  domestic  supply,  30,  31. 

heating,  (see  water  heating). 

stills,  255.  r 

thermal,  characteristics  of,  94. 

weight  of,  at  various  temperatures,  270. 

Water  heating,  17,  78,  93-114. 
automatic,  104-107. 
circulation,  102. 
comparative  cost  of,  93. 
energy  required  for,  95. 
faucets,  99. 

features  of  water  heaters,  103. 
for  hotels  and  restaurants,  78. 
immersion  units,  17,  101. 
instantaneous,  99. 

lagging  of  tanks  and  piping,  (see  lagging), 
losses,  96,  97. 
methods  of,  98. 

on  range  cooking  surface,  30,  31. 
plumbing  for,  107,   (see  plumbing), 
thermal  storage,  99,  107-114. 

Wax,  burning-in  irons,  256. 
knife  heater,  256. 

Weight  reducing  cabinet,  257. 

Welding,  197-213. 
arc,  198-206. 

apparatus,  201,  202. 
cost  of,  203.  204. 
cutting,  206. 
energy  required,  202. 
materials,  204,  205. 
operations,  203. 
systems  of,  199,  201. 
Bernardos,  199. 
Slavianoff,  199. 
Zerener,  201. 
electrodes,  199,  201,  202,  204. 
nature  of,  197. 
processes,  197,  198. 
chemical,  198. 
electric,  198. 
hot  flame,  or  gas,  197. 
smith,  197. 
resistance,  206-213. 
apparatus,  207. 
applications,  207,  208. 
character  of,  211. 
classification,  209-210. 
butt,  209.  210. 
butt  seam,  209. 


286  INDEX 

cross,  209. 

jump,  209. 

lap   or  seam,   209. 

spot,  209,  210. 

tee,  209. 
costs,   212. 

energy  required,  212,  213. 
of  various  metals,  209. 
Thomson  process,  206. 
seam,  204. 

Wires,  carrying  capacity,  19. 

service,  24. 
Wiring,  flexible  metallic  conduit,  23. 

flexible  steel  armored  conductor,  23. 

for  air  heaters,  123,  124. 

knob  and  cleat,  21. 

knob  and  tube,  22. 

metal  moulding,  22. 

methods  of,  19,  21. 

rigid  conduit,  22. 

wooden  moulding,  22. 
Wood,  calorific  value  of,  271. 

Yarn  conditioning  oven,  257. 


UNIVERSITY    OF    CALIFORNIA 
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